Really depends on what you want, there is a company (Project Repat) that does a very basic, sew the squares, back with fleece, no quilting, for around $100. The prices really vary. Make sure you see pictures of the work the person has done so you know what to expect.
I do basic ones for the seniors at church and don't charge for my time (church buys the fleece for back). They are actually pretty easy to do, if you want to attempt it yourself.