Agreed on both of those, I would probably also say it tends to be in sets that have an aesthetically pleasing or sets where people like the styles or subsets - there's Allen and Ginter set-builders. Gypsy Queen had adherents. Basically the cheaper the product is and the more uniform/cohesive the look is, the more likely it's a set builder.
In terms of the Flagship Set being cheating, it cheats out of the experience but it's way, way, way more cost efficient and often the complete sets have a bonus with them, if I collected Flagship I'd buy a complete set any day. I do think people tend to not build it as much as you can buy a factory complete set for like $50, or an Ebay put together version for less than that, but some people do.
For online red flags, tough question. My general rules
- Don't buy single packs. It's far too easy for people to buy a box, get the hit(s), and then list the non-hit packs for sale. I'd only ever buy single packs on impulse as a pure rip or, MAYBE, from an LCS that keeps all of their packs behind the counter - definitely not online. There's an argument that boxes represent the same risk, but that's only a concern in products that have true "case hits" and if you're legitimately hunting for case hits where sellers will prune for them, that's many stages away from where you or I collect.
- I don't buy through Amazon - it's generally overpriced with no quality control or accountability for sellers. I do think eBay is relatively safe - look at feedback, look for sealed boxes - high volume box sellers aren't nearly as likely to bother with any funny games and there's sellers with hundreds of thousands of sales on the platform.
- Generally, your "big distributor" seller sites (Dave and Adam, Blowout Cards, etc.) are very safe as are your direct retailers (Topps, Panini) and, for retail, your big box stores (Target, Walmart, Barnes and Noble, Books a Million) are similarly fine. If you're not feeling great about eBay, definitely go this route. You'll likely pay a smidge more but when we did card breaks here the breakers often bought from D&A or Blowout and we got some amazing stuff that would not be in a tampered case.
- In any kind of sale, do not pay for anything via an unprotected payment method. The card world is full of scammers and they will not hesitate to take your money and dip. Use PayPal Goods and Services or a protected equivalent.
As someone who has been really too much into it the last few years, here's a mix of products I'd recommend that won't break the bank and, while it absolutely does not guarantee you anything, still offer a chance to hit something fun. My list of "I won't go poor but I want to rip" selections - different types of listings so not all may be to your taste.
2024 Bowman (Blasters - $30) - Bowman this year is a product I genuinely like that is more expensive than it should be. However, I think the blasters give you like 80% of the Bowman fun (sadly i don't think you can get the Anime case hits out of retail or the rarest parallels) at good odds and a much more tenable price. This is a prospect heavy product, but colored frames/borders aren't impossible, there's good variety, and there's always the chance you get a $100, $200, $500 card out of them (more likely not but it's possible at least).
2023 Panini Elite Extra Edition (Hobby Box - $75 (Ebay) - EEE is an unlicensed product which means it doesn't have team logos/licensing and sell for a lot less, but if you want autographs of minor leaguers that matter in high quantity for low prices, EEE is great. 8 autographs and 2 relics per box for $75 - the design elements are a bit louder and I think quite fun. There are a lot of people who won't collect unlicensed but since Panini lost the license, the cost equation has been a lot more reasonable.
Topps Pro Debut holds a similar niche in the licensed department - I just think the design is less fun and you're trading half of your hits for the license of minor league teams.
2023 Topps Stadium Club (Blasters - $25, Compact Box - $80) - I don't like this
as much at the current prices cost - Compact was $60-70 and Hobby at $110-120 would be my point, but photography is great, they increased the number and types of rarer inserts, on card autos are always winners, and there's always a chance at something great.
2023 Topps Allen and Ginter (Hobby Box - $125) - I think this is the best A&G in recent memory. The strong rookie checklist and quality fun sets are nice, but they key draw are the very high end chases on the framed auto checklist, and the newer parallels that are really nice. This has gone up about $20-25 in price since release and even at $100 you're not making your money back, but it is a fun rip and the framed autos are one of my favorite annual autograph hunts.
2023 or 2024 Big League (Hobby Box - $40-$50) - It's a product that gets boring quickly and the cooler borders/frames are difficult to find, but it's cheap, it has a good auto checklist (sticker autos but still), and some rare inserts that look great while not costing much more than what you get at WallyWorld. It's for kids but it works.
2022 Topps Update (Blaster Box -$30 - $35) - We talked about this a bit with Heritage High Number, but the Topps Update checklist has the flagship Bobby Witt Jr., Julio Rodriguez, CJ Abrams, Hunter Green, George Kirby, Bryson Stott, Jeremy Pena, Seiya Suzuki, and Steven Kwan rookie card. It wasn't printed that much relative to other Topps sets either. They also have short prints, variations, and a lot of fun stuff. A sneaky choice if you want a more robust box is the
2022 Topps Baseball UK edition - a regional exclusive release with a lot of those update names, some different parallels, it's not that bad for $110-$120 a box (though probably a bit too pricy)
2022 Topps Heritage High Number (Hobby Box - $60) - We talked about this, floor is very high for a Heritage product and has some great upside. Money where my mouth is, I put in an order for a box based on this discussion
2022 Topps Chrome Platinum (Blaster - $30) - Bergs can tell you all about this, and Hobby Box prices are now a bit much ($160 per), and I never liked the Lite product, but the cards look great, have a ton of amazing colors, nice on card autos, and a slew of retired players. Great product for this year and looking forward to the upcoming release.
2022 Topps Chrome Sonic Lite ($40 a box) - This isn't a good product. It's a bad product. However, it was so poorly received and overprinted it's now like 50% of its retail price and...that's not as bad? The sonic refractors are good looking cards, Youthquakes are a fun insert, Topps Chrome is still Topps Chrome, the autos are nearly impossible to hit but $40? Again it's a lot of opening for $40.
2022 Panini Diamond Kings ($70-$80 a Hobby Box?) - It is Panini and it's unlicensed, but it is a fun product in my view. Has great border/framed parallels, good auto checklist, good relic checklist, good artsy design. I like the product a ton.
As we chatted on, opening packs will almost always be a loss, but if you gave me like $500 and said "buy someone a bunch of a boxes to spend a day opening and maybe find something fun", I think a mix of these would be my suggestion.