I should really make something like that for myself, especially when I get into high-level crafting. As of right now, I only just sell whatever stuff I pick up from monsters and leves, but I got so tired of running back and forth that I just look at an item and slap a price on it based on it's level and power and if I remember seeing it being sold at an NPC for a certain price or not. Not to mention the price differences in Ul'dah compared to the other main cities.