i see you, thanks! so what kinds of avatar items do you like? Most items you can find on the market but you must buy the traders card for 500 gold. it's a good deal on the long run, you get all the super special stuff from there.
when you find some add them to your wish list. gaia cash is bought with real money, gaia gold is them main currency of the market, most convert gaia cash into gold to buy super cool stuff for less.
you can buy items from shops but, how do i say nicely...they are kind of cheap looking. items found on the market are more rare and most prefer to spend their gold on more expensive items. also, with special items you get a choice of equipping one of the pieces, you must buy multiple copies if you want to equip a different piece of the same item.