This isn't a normal online store like ebay or amazon. This is a marketplace to upgrade your profile. Your points are your post's.
Example: If you have 500 post's and you buy something 10 points, after you buy it you will end up with 490 points.
Admins have unlimited points.

$1 - Avatar
$10 - Signature
$30 - Advertise/ in advertising forum
$50 - Sig Adversing
$250 - Mod/ 1 day
$500 - Username change
$1000 - Create/Mod your own Usergroup

These are the points. If you want to buy something, say what you want to buy then i will review the message and make sure you have that much.