As well as I know, maya items requires 2000 qi to be unlocked, but I saw a people that only have 500 qi can wear a maya relax. How can he bought it?

Info:
http://forum.toribash.com/tori_shop_item.php?id=1165
http://forum.toribash.com/tori_item.php?invid=2597967

Here is the user achievement:
http://forum.toribash.com/tori_achie...ame=LoneSkills

Qi restrictions are only ignored when the items are sent by special users e.g. gm prizes, marketeers, TSAs. Just to be clear, there are no such things as "no-qi items".