And of course, you can also use these methods to sell items that you have :P
 
What kinds of clothes and items are there?
Ah, therein lies the rub. There are six general types of clothes/items on Gaia.

The first is commons. These are the stuff sold in stores. Basically, if you have enough money, you can get them. Their prices stay the same, and Gaia never runs out of these items.

The second is rares and uncommons. These are clothes and items that you get during the treasure chest or the gift box random event. Random event, you ask? Yeah. At random times (note the term "random"), you will get a  beside your avvy. Yeah, it looks just like that. It's accompanied by a flying treasure chest or a flying gift or a glowing pink link. You need to click on these things. If you click on the flying chest or gift, you will get it in your inventory. Then you can open them to get clothes or items that are not found in stores. If you click on a pink link, your gold will go up by 1000. You can buy and sell rares and uncommons in the Exchange and in the Marketplace.