No, but you can set item levels, and use both the "keep lower level items" and "get all lower level items" flags to do something very close to what you're proposing. The only problem is that you can't keep collecting level 1 items to get anything more than a level 2 item, can't keep collecting level 2 items to get more than a level 3 item, and so on.

[b]BUT/b] you can use the above mentioned flags, and have shops selling level 4 items, level 16 items, or whatever.

I can always just bring in the magic meter if this proves an unpopular usage.