In case anyone is wondering, don't try to get tricky with the boxes and put things in for a high price, you'll most likely only hurt yourself. I put simple items that usually only sell for 10 at 20 or 30, and they do actually sell occasionally, and that feels like a good win if I have some extras of something clogging my inventory, because that's technically already double or triple what I'd otherwise have made. But if you try to get funny with it and put up fruit for 500 bells, not only will you not sell that item, but the game has a really poor design whereby if you want to take back a listing, you can only do so by losing the item for no profit. So putting in something silly like that will only permanently block your potential selling spaces or result in a loss of 10 bells you'd have gotten from at least selling it in game.
And let me add that if you think it's no big deal to leave annoyingly overpriced things in your slots forever in the hope that one day someone might be tricked into paying that, the first row of slots are particularly important because so far as I can see, if I do actually go looking through people's boxes for something, it will only show the first row of their items with no indication of what else they might be selling. Therefore, even if you do put more reasonable listings lower down, people are unlikely to have the time to visit every camp individually. They will probably be like me and only have time to load the preview of the top row and the second I see silly prices I just move on.
I'd also like to add that there seems to be a bit of a misguided trend whereby people are listing the rarest bugs and fish for the highest prices in the top slots (presumably because they think someone will desperately need one and be willing to pay it to finish the request in time). However, at least at the time of my writing this at a reasonably high level and before worldwide release, I have seen no proof in my game or anyone else's that these rarest creatures are ever requested. So in fact, there'd be pretty much no reason ever for someone to buy one instead of waiting to find it themselves, and it'd be unlikely that anyone would want to be purchasing and holding onto them in advance of them being needed given how restricted the storage space already is. So putting in the more common items is in fact better for everyone.
I'd also like to point out that even if these creatures should become requested, unless the request structure itself changes significantly, it wouldn't be worth paying the prices that people are asking for them anyway, because as it currently stands if you get a medium rarity request like the horned dynastid or red snapper, you get paid the same amount you would have to sell it in game anyway, the only loss is the couple of relationship points and maybe a cotton or something, which is not worth taking a 1k+ loss considering the prices people list football fish for
If you'd like an additional market box tip, I'd also suggest taking advantage of the top row, cheap commons strategy, by specifically putting only one of each thing rather than bunches of things, and in doing so, only put one of each type in each of the first row slots. So for example, instead of putting a whole first row of orange bunches of 3, and then the other fruits after that, I think it would be more effective to sell each fruit one per slot (and considering the slots unlock naturally overtime having lots of slots isn't too hard). So placing 1 orange for 20-30, 1 apple for 20-30, 1 conch for 20-30 and 1 coral for 20-30, and then anything else individually in any order below that is the best way to go. It makes it more flexible for a buyer who may just need one quick apple and not 10 for a heap of bells, but also means that if a buyer is after a lot, they will see your reasonable prices and come looking for the rest of your listings anyway.
