Sherry, yes, the pricing depends on the type and amount of quilting you want, from a simple edge to edge to high-end custom. Most longarm quilters charge by the square inch, and that generally starts around .015 & goes up from there.
Do not baste; your top, batting and backing all get loaded on the machine in a very specfic way, and the quilter will stabilize as needed, as he/she quilts.
I would advise you to start with a LQS and inquire about LA quilters in your area. Ask to see examples of their work, the pricing structure, turn around time, etc. - many shops have their own, in-house machine.
Some longarmers also sell the batting and backing so all you have to supply is the top, or you can send your own batt & backing to meet the quilter's requirements, generally both will need to be about 8" bigger than your top, both long & wide.