Why do you suggest that?

I sold used books back in the day (not FBA; at one point I had 10000+ books kicking around my house, gotten mostly from estate sales and craigslist "a science fiction fan has died, and I don't want the books" posts) This was before it was common to see people with barcodes at booksales.

I wrote some software to do pricing (I used regexes to read the REST API call returns rather than proper REST libraries. lol. And it worked) and to go from mass market paperback barcodes -> ISBNs (the hardcovers usually have the ISBN on barcode, the mass market paperback have a weird system where the first bit of the barcode is a publisher specific prefix, second part is the last part of the ISBN. When you see a prefix you don't know, I had the system ask the person inputing to manually type in the barcode, then I knew that publisher prefix.)

I guess the lesson was that most books not only sell for under a dollar, (you make about another dollar in shipping? More if a user buys more than one thing from you, but I don't think amazon has a system to encourage this) but most books just don't sell, even with 10K books, if you didn't add new inventory, you'd sell a book or two every two weeks, once the in-demand books sold, which would happen within a few months of getting a new load of books. (note, uh, it wasn't like there were a lot of expensive books kicking around unsold... nearly all the more than a dollar books sold during the first few months. After that, it was all penny books that didn't sell. I think the problem was that the books would sell, but that the market wouldn't bear a price high enough to ship them one at a time. If amazon had a way of getting users discounts if they bought in a way that allowed a seller to aggrigate shipping, a lot of those could have been moved.)

(I mean, my goal wasn't to sell books, my goal was to write a platform. And... maybe there is still room for that? I mean, amazon is terrible for selling those books nobody wants to pay money for (and a lot of those are super popular books that people want, it's just they are also super common, and you aren't going to get $4 or whatever for a book that was a book of the month book that everyone's mother has a copy of.); the buyer has to pay like $3+ per book, of which the seller gets to keep like a dollar, but because there's no encouragement for the buyer to buy all from the same seller, even if the buyer buys a lot of books (which is common for those books; As a child, I was known to go to those friends of the library booksales and come home with my body weight in books at like $0.05 to $0.10 per) - so I think that if you figured out how to make it more like the friends of the library situation, and pay less for shipping, you could move a lot of these books. But another lesson, for me, is that you want to work with someone doing the actual selling, actually doing the selling is a lot of work and gives you all sorts of urgent problems and ends up taking away time from platform development)

I guess what I'm saying is that I don't see a lot of lessons here for FBA; i mean, in that market, pricing and reputation are important, but you don't do any advertising or ad copy. (maybe I would have done better had I done so? but the amazon platform doesn't have a lot of room for that.)

I mean, the FBA play I've wanted to do is to look for the things that I buy and love that amazon doesn't sell, say, like Jovy brand Fruit roll-ups (which are there but even the bulk packs are like 3x what you pay in the store) - of course, uh, grocery is traditionally not super high margin, and people are way more price sensitive of groceries than other goods, and considering the... issues of FBA, I would have to sell in large bulk packs, and even then I'm not sure what kinda margin I would get out of it, so I haven't tried... but I kinda don't think most of the bookselling lessons would be applicable. (other than, I guess, that you have a minimum per-unit price because shipping, and that at that minimum price, there are a lot of things that you just can't move.)