A post-E4 shop containing expensive evolutionary items sounds like a good idea.
Could you get any gen 2 pokes in fire red before getting the national dex?
Anywho, as the tags suggest, this better belongs in this thread http://forums.pokemmo.eu/index.php?/topic/223-high-level-item-store/
In there it talks about a store that sells EV training items and more competitive held items. Seems like a great place to also sell metal coats and dragon scales.