I like inserts, and probably have more of them than 1shts. I keep picking them up as they are for peanuts (not Ari's friend, I mean cheap). You can get a nice poster for a fiver, and as said they fit in those tight places on the wall, so very handy.
Some nice ones posted above, and a first rate kitchen floor...
I'd just like to say, if you like them they are worth collecting. If you want them to be worth something don't buy them, as that is not the reason to buy a poster, or any collectable. Buy what you LIKE and enjoy it for what it is.