You cannot change the qi of items.
A YOUshop is a shop that you make, selling items at whatever price you want.
People can buy from your shop, purchase items like chronos torso or anything. You can also purchase from other peoples shops.
If your shop gets banned, you do not get your items back I think.
ToriShop sells items at a nromal price. But the YOUshop sells them for up to 99% cheaper, mostly around 70% cheaper.
http://forum.toribash.com/market_view_shops.php?page=1
Normal shop page.
The Deal Finder is a search tool that helps you find the cheapest items.
So if I type Helios Torso, it takes me to the lower helios torso there is to buy.