There's not really a single "going rate." It really depends on what style of quilting you want. For pantograms most longarmers in my area charge a penny and a half a square inch. If you use an average size for a queen size quilt of 84 X 92 the quilting would be 115.92 plus possibly thread and batting charges and in some places taxes. A pantogram is a single, edge to edge, all over quilt design. Once you get into custom and heirloom quilting the prices jump considerably. A local longarm quilter here charges 5 cents a square inch for heavy custom work and 7 cents for heirloom work. There are also additional charges for turning the quilt and thread changes. So that same 84 X 92 inch quilt would cost 540.96 plus turning, thread changes, batting and taxes for heirloom quilting.
Quilting can make take a quilt from ordinary to spectacular or it can ruin it. I saw a Vintage Valentine quilt at the quilt show in Loveland that was pretty much ruined by the quilting. The Vintage Valentine quilt is a gorgeous block of the month appliqued quilt and the quilting on that one was a simple all over meander. It made what should have been a spectacular quilt very ordinary, verging on ugly.