Magic Potion Bottles acquired in Augy's Basement (Area: Ring 99 - Ticker Square - Interiors) from the npc Augy Baxter Gropplehurst through the dialogue option 3 (I would like to buy a bundle of empty bottles for brewing, please) can be sold in shops because they are not marked as stolen.
If you make your appraise check at Augy's basement, you can buy ten bottles for 15 gold pieces. And each of these bottles can be sold for 3 gold pieces individually. Allowing for an infinite money exploit (For the very bored).