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