Amazon EC2, which hosts Cydia's Internal website, has been having extreme issues for 40 hours now. This outage affects the ablility to purchase paid products, the theme center, and Manage Account. I (Saurik) have been sleeping in hour-and-a-halfs shifts since this outage began in order to keep a dialog open with Amazon "Premium Support" regarding this issue. Recently, enough access was recovered in order for me to modify the home page to add this message. Unfortunately, Amazon's status and ETAs have been confusingly vague and highly optimistic throughout the experience, causing me to be unable to make good decisions about disaster recovery choices. At this time, the latest news from Amazon AWS (as of two hours ago) was "that this will take 3-4 hours until full access is restored". Meanwhile, premium support has asked engineering to prioritize recovering Cydia's infrastructure. (For those interested in this sort of thing: this is the same Amazon EC2 outage that has been affecting other sites, like reddit and foursquare).
: After 86 Hours of Downtime Cydia is back up fully running the store and you are now allowed to purchase packages. Thanks for your patience.
