How the heck do you “sell out” of an app?
They capped sales because their servers are overwhelmed. Because Apple has dictated “NO FLASH” on iDevices, Skyfire gets around that by transcoding flash websites on their own servers, then sending the results to your phone in another format.
Essentially, demand was so high that Skyfire’s servers can’t handle all the bandwidth requests. So until they roll out more servers, they’re cutting off sales.