I'd like to suggest you make the database downloadable, in something easy to manipulate, like spreadsheet form, or something you can stick right back into a local copy of your database.
and... I'd like to dream about synchronizing local copies of your collection with your collection listed here. (just keeping track of what you have, not new entries) That way you could do something like update your collection while on a laptop checking your storage boxes in the basement, and then upload and DING, done. Pretty sure databases have some feature like that, right?
oh right. I mentioned filters. It would be nice if you could maybe save filter settings automatically, so you could do things like filter out packaging variants. I don't know. That might be really hard to distinguish from the figures inside being actual variants or exactly the same. (like the Wal-Mart Skyboom shield Mini-Cons that were packaged with storage tins and Cybertron deluxes. The Mini-Cons are different, but the deluxes aren't. Meanwhile, there are Cybertron deluxe 2-packs that are unchanged.)
BTW, with the UPC #s and whatnot, I had found some packages had more than one. On each part of the packaging that was separate (the card back, the insert inside the bubble) the number was slightly different. I'll try to fish around for a specific example at some point. I also know the #s change sometimes in different countries (because the packaging is different, for things like bilingual text. different packaging, different #)
edit: ok, I found an example. (lucky for you, I keep the packaging of everything) Universe Blackarachnia. P/N 6252740000 on the card insert in the bubble. on the card back, P/N 6238460300. Hrm. there's more numbers. C-1063A. and then indented: 32241.
I notice that the number you keep track of, "Product Code/Assortment #" has... part of the UPC (or whatever the bar-code is called). Do all Transformers have the same beginning of the UPC? 0 76930 ##### 4 ? (not sure about those single digits on the outside) *checks other packaging* nope. Universe Micromaster Devastator has 6 53569 00352 6. huh... and his product code doesn't match his UPC # the way Blackarachnia does. His Product code is 29472/29460 Asst.
So I guess my info is only useful for people collecting packaging variants, including bilingual/unilingual/etc.
Oh, and I had mentioned earlier with xZAOx, which he confirmed was a feature he was going to implement in his project, a way to match people's wanted toys with available toys. as well as things like maximum price to pay, or minimum price taken, perhaps with a second number for each to set a starting price slightly more ideal for the person offering/looking.
For your system, this would of course require an additional field, one of "for sale", as opposed to "in my collection". (heh. in MY toys, the line between the two is sometimes not clear at all... )