[Palmer ofShinra]

In short... it reads your user info, gets your Gil, which is a custom user field.

It then checks your Gil against what you wish to purchase. If you don't have enough, it says so.

Otherwise you get a form to fill in with the pertinent details.

Submit the form and it deducts the appropriate amount of Gil and does whatever it's supposed to do.

Pretty simple all told...

I'm probably going to throw together a quasi-hack qith the various code snippets I used that you can use yourself to make it.