Android market was opened for paid applications (for US and UK only) in mid of February(20th, I think). There aren't many paid application as yet. If you are a registered Android developer, you can visit Android Market and actually see the number of downloads and other application statistics for paid applications.
Have you heard how people are doing in terms of sales for their apps in the Google App Market?
Lousy, for any number of reasons:
No major media attention, as opposed to iPhone App Store rollout, so non-developers may not even realize there is a change
There are "only" a million or so devices out there, so unless you have an app that everyone needs, you won't get many sales just based upon sheer statistics
Developers saw the "land rush" that was the iPhone App Store, and assumed they could just write an app and have it sell lots of copies, without bothering with pesky things like "marketing" or "promotion" or "public relations"
The Android Market is only available to users in some countries, cutting into the overall user base
The Android Market is not available (at present) to users with ADP1 developer phones, cutting into the overall user base
Etc., so on, and so forth
Developers have a bit of "irrational exuberance" -- many fail to realize that the iPhone App Store was a once-in-a-decade sort of event and not everything will behave quite like that. Selling dozens of copies a week with no marketing effort is pretty impressive in just about any other market...but at a few dollars per copy, developers will not get rich.