people won't buy your stuff just because its there, so in honesty its unlikely someone will be browsing itunes or amazon, come across your stuff and buy it.

I'd pick a few careful partners and work hard at promoting your relationship with them. Trackit down, juno, beatport - these are all portals that people use regularly to buy a certain type of music.

All of them have a recommendation element that can help drive sales. "users who bought this also bought this" etc etc. Ultimately nobody is going to buy your records without listening to them first, so you need some way of making people want to listen.

Showing up your stuff in relevant portals, with promotion and recommendation in relevant channels should be your best bet.

And personally, I'd forget about the money side of things. Beatport might give you fractionally less, but you're not going to get rich anyway. Each download from ANY portal gives you someone who could recommend you to other people, who may go on to buy your stuff.

You want to get heard by as many people as possible. Money will come as a consequence of being well known and well liked, not by being well protected.

my 2 cents mate