Learning more about PAID deskop music players market in 2011

Considering developing a software product which will enhance the control ability of existing media players for audio enthusiasts (audiophiles, htpc users and more).
The first step is to estimate the market size for sales of PAID players such as JRIVER.com & AlbumPlayer.com.
Does anyone have access to similar information? (preferably: how many people PAY for premium desktop media players; secondary: how many downloads of premium free players e.g. the above or others: Winamp, Foobar, Media Monkey etc).

Thanks
-Matt

In a case like this good keyword research will show you the size of the online market. The google adwords keyword tool, is a free way to see what keywords are being searched for.

You can also use google insights and google trends to get a general idea of where the market is going too.

Another idea would be to call the company in question, say you're from the IRS and ask for a copy of their last financial accounts. I've never done this.. but I Imagine it could work. Or you could call them and just ask... the worst case scenario is they'll tell you to get lost.