When a character wishes to purchase an item from the store all he or she need do is open a thread in the purchases forum at the role-playing arena which includes the following...
1. What item the character wishes to purchase
2. How much the item costs
3. The character's perception XP if the item requires a perception check.
Some items require what is called a Perception Check. Perception checks exist to ensure that some items are harder for characters to get than other items. Mandalorian armor for example is extremely rare and the difficulty of the perception check is very high to simulate the difficulty of locating a set of armor available for purchase.
Perception checks pit the difficulty rating of the item which is typically 100, 200, or 250 against the characters perception XP.
If a character fails a perception check on an item he or she may try again once more that week for a total of two tries. After that he or she will have to wait until the next week to try again.