I should cross-post this here.
Alright, some quick tips....
This link will straight up add it to your cart
http://www.gamersgate.com/shop/addtocart?sku=DDB-BETHESDANYC
IAMANELDERGEEK is a 5% discount code. Applying it will incur another page reload (eew). Only the bravest of CAGs will try to buy blue coins first and double dip on the code. I did.*
GG checkout sends me to paypal, sign in to paypal, click button, get sent to GG with a long url with a paypal token in the url (probably timeout and reload needed) sends me to the GG receipt page. I had to reload on timeouts when being sent to and returning from paypal
after the confirm button on paypal you should get a long url to gamersgate.com/something&token(obviously from paypal). I had to reload on that
Quick tip on seeing if it went through, visit
https://www.gamersgate.com/shop/orderdetails/### where the last number (###) would be the number at
https://www.gamersgate.com/shop/payment/### which is also your GG order id.
You can see it in your GG library at
http://www.gamersgate.com/account/games
* I had $20 in blue coins sitting in my account since the good old days of the IGN discount that I wanted to use.