Brokerages and resellers take their share of each sale. A normal reseller percentage is 30%, paying the vendor 70%. Several (but not all) brokerages take 50%.

Also, some sites have driven down costs to acquire your business - especially since the economy hit the dirt in 2008, setting expectations of $1.99 per product. It is hard to sustain a product on that. Those $1.99 sites are invariably brokerages that work on volume. That isn't really good for the artist.

Piracy also has its influence.

If you buy directly from the vendor, they get 100% of the sale plus they can make new products and let you know about it - rather than their stuff being drowned in a sea of other stuff.

Everyone likes free or low priced stuff.  But it has driven many vendors out of business.

The smartest business route is to have your own site, then sell on one or two "volume" sites and partner sites.

Best regards,

Lynn Fredricks
Mirye Software Publishing
http://www.mirye.net