I think it sounds a little low as well, as bj said just to have a quilt longarmed will run you $100. How were you planning to quilt it? Madolyn made a great list, but I would add a pack of needles to that list, you change the needles once every eight hours of sewing, and at the very least it would be good to start a new quilt with a fresh one. I've found that quilting on a sewing machine goes through needles faster.
Also making binding vs buying it, once you know how you'll never forget and it's rather easy, but that's time consuming cutting, sewing, and pressing.
Oh and don't forget a new rotary cutting blade. I borrowed my mom's rotary cutter and she warned me it might need a new blade, but it felt sharp to me so I kept using it, I used it through cutting more than 3 1/2 quilts expending way more effort than otherwise would have been needed, and as we all know the more pressure you use the more likely you will cut yourself, and it would simply not do to bleed on the quilt. :) I've read here that it's best to start with a new blade with the start of a new quilt.