I've got a couple of tips for you:
1. See samples of the work, either in pictures or in person
2. What is included in the cost of the qulting? What I mean is, sometimes there are charges you don't expect. Make sure the contract or work order is clear and that you get what you pay for.
3. How does the LAQer charge for their work? Some charge by the sq inch, some by the sq yard, some by the number of bobbins used, etc. Is there a minimum cost regardless of the size of the top.
4. Are there different price categories for different types of quilting?
5. References?
6. What is the turn around time for completion of the quilt?