Like others I do not try to sell my self short but I also know I am not going to sell a $1000 quilt to the average person.
You didn't say what size quilt you have been asked to make--this will affect the price drastically. I am not sure what your skills are either which will also play a part in the price. If you get to pick the fabric out and the pattern you could get away with a YBR or Turning 20 in a lap size or baby size for about $150 and finish it in about 2 days time from start to finish. If you are doing something with paper piecing (which I wouldn't ever do for customer) you will have to charge a whole lot more, if you are making a queen or king size quilt you will or should be charging the $800-$1000.
If you make a quilts for people you have to look for fabric on sale and when it is buy as much as you can afford. This is how a profit is made-- at least for me it is.
If I have the fabric to make quilt from my stash and I all ready own the pattern, I am long arm quilter so I can get wholesale cost for batting and thread that makes my initial cost is lower than the average then and I make more.
Does that make sense? It is really early here and I haven't had a full coffee yet so it might be all jumbled.
I hope you are able to figure it out and get paid wisely for your time and most importantly don't forget to come and post pictures of the finished quilt so we can ooohhh and aahhhh over its beauty. :-)
Happy Quilting
T