I'm sure I have a couple hundred of these just from doing idocs. Most are the 125 item limit variety (if a house falls and there is stuff in the moving crate you can get these that way), some are the old co-owner converted 25 item limit boxes.
I had no idea they're going for so much nowadays, I think I usually put them out at 50k or something. Too funny.
Ok so you can make your own, though it sounds like quite a hassle - all you have to do is have an account without a house, place a house, force lots of stuff in the moving crate so you'll get lots of boxes (you can check the moving crate beforehand to see how many boxes you'll be netting, and even empty them out to 1 item each so that when you pick them up later you wont get overloaded), then condemn that house by placing another house, then wait out the decay timer, then fight with other idocer's. If you make it public and leave it as a blank plot that will probably cut down on the number of people you'll have to wrassle with, you'd also have to keep a close eye on the house sign since it will no doubt fall at a weird time (another thing that will keep regular campers away).
Convoluted, but I'm sure it would work.
