Rule of thumb.....charge 3 times what you paid for you materials.
You can come down a bit on the price, but be forwarned....most people who don't quilt or have a clue about quilting will think you are charging too much. I had a couple quilts in the craft fair I did and the prices were REALLY cheap. The baby quilt I had was priced at $50 and had a lady tell me that it was WAAAY too much money. The other 2 I had were twin/lap size and I had them at $100. People would mutter that it was too much to spend on the quilts.
I would ask these people what is the maximum they are willing to spend. IF it's an inconcieveable number they come up with, explain to them the "art of quilting". Once they understand, they may pay what you are wanting and then again, they may not.