Some Gear with built in speed boost
Spoiler:
check out http://www.gorgonexplorer.com/build-planner. You can check skills to see what treasures effects affect speed. Not sure at the moment what names would indicate a speed boost treasure effect for any given skill, there are probably tons of names.
To learn more about shopkeeping talk to Selphie
On you selling question, if you are talking consignment, I'm pretty sure there are no advanced option with it. You put an item in and set a price that is it. Personally I haven't consigned anything in a really long time, so only going by how I remember it.