I don't disagree, but I've been continually impressed with how "pound shops" (dollar/99 cent stores in the US) have coped between the mid 90s and now. It seems advances in logistics, manufacturing and the ease of international trade have counteracted inflation to a certain point, at least when it comes to the cheap crud those stores tend to sell :-)
J.C. Penny was founded in 1902 and for years everything in the store cost a penny :). Same goes for the price of coke that stayed at a penny for 70+ years :).
So I guess in the very long run $5 isn't sustainable (and they're going at that direction btw... $5 is just the starting point nowadays)