The thing that bugs me is the way you do highlights in the tail (and sometimes mane). You just use the dodge tool and draw a bunch of thin lines straight across, which really detract from your pictures. Again, this is just my opinion. If you were to pay a little more attention to where the highlight would actually lay, it would add a lot to your pictures. Everything else is really awesome though, I like your unique style.
Not sure how much of a market there is for digital works though. You should talk to a few people, maybe put an ad up and charge a small fee and see how much interest you get.
I've been doing commission work now for about 5 years and have found that the work load fluctuates dramatically. I'll go for months with no work, and then have times like now, where I have too much work and need to turn people away.
All I can say is advertise a bit, charge only a small rate and see what you get. If there is no market or little market, you cannot charge much at all or you won't get anything.
I don't get how people can do digital artwork it looks so complicated!!! I'll stick with my good old fashioned pencil in hand work :P