I'm a Linux developer myself, and while I'm not an artist, I've worked with artists, quite a number of whom have stated that they'd definitely make the switch to Linux if they had good alternatives to Photoshop.
I definitely understand this sentiment, and unfortunately the Linux community has gotten this unfair rap for being against non-free (as in price) software, we certainly aren't. I personally have spent 100$ on an application called hopper, as well as 45$ for another application called 010 Editor. Not to mention dozens of games. So there is a definite market for for-profit applications in the Linux community.