Once you enter one of the three Imperial-occupied towns, head upstairs and into the Pub. Follow the “path” to find a clock in the hall between the Pub and the armor shop; examine it for an Elixir .
Examine a pot in the weapon shop for an Ether , and examine a barrel near the Inn for a Hi-Potion . Otherwise, shopping. It is rather disappointing. The Inn is pointless; the Blackjack is just outside of town.
Buy some weapon upgrades – most likely a Bastard Sword or two, maybe, and the Venom Claws for Sabin. Armor-wise, you can’t really get much better than the Priest’s Miters.
That’s all. Leave.