After all 10 gigs is only 25 to 40 images
Actually 10 GB is 1000 high-res images @10MB each. Most high-res JPGs are less than 10MB.
Bare hosting often costs more than that.
Yeah, my bad. I was looking at my raw images and not the JPGs. And if 10 GB costs you more than $10 a month you need to find another host. I'm paying $30 a month for a terrabyte of space to host my own personal web sites (and those of most of my family).
Like I said, I think your overall concept is a good one and thank you for offering such a service, but your service is unproven. There's no guarantee that you'll ever sell a single image, much less enough images for an artist to cover your monthly fee. So hamstringing them with limited services is a bad move in my opinion. You should be providing all artists every possible tool and chance to be successful at selling through your service. Otherwise you are setting up them and yourself for failure.