I have multiple levels of VIP. I'd like to allow people to upgrade to a higher level at a reduced price, basically taking how much their level costs and deducting it. This of course would only work in a payment chain. I also need Amazon Payments and Google Checkout as two other forms of payment. This way my users aren't forced to use Paypal. Right now I have two pages setup for Amazon and Google that have a big list of buttons for the proper account upgrades.