Here comes App Store Expense Monitor!
I know the stats will change constantly, but I suppose we can all declare what we've amassed thus far. :)
I'll start the ball rolling then. This isn't my complete list, only what's on my MacBook. (my iMac indicated at least 2000+ apps and I'm trying to get it to manage all of it soon)
Total Amount: $817.80
Number of Apps: 1592