Do you know what kind of design she's doing on the quilt? That has a definite impact on the cost. An overall meander is generally the least expensive, and I've seen the charge for that from .01 to .02 per square inch. If she's getting a more intricate design, the charge will be higher.
There are several factors, and while I'm sure some quilters who have computerized have raised their prices, I don't think most have (just based on what I've read - I don't have any specifics). The type of design has a bearing on the cost. Specialty threads can increase the cost. The geographic area in which the quilting is done can have an impact (what the market will bear). I suppose that even the experience of the quilter - for instance, if she's won a lot of awards and is well-known for her work - could have an impact.
Another thing to keep in mind is that many LA quilters have a minimum charge, and the client may decide to pay a slightly higher per square inch charge to get a more intricate design for little additional cost. For instance, let's say the LAer has a minimum charge of $50, and she charges .01 per sq. inch for an overall meander. On a 4000 sq. in. quilt, that would be $40, but she will charge $50. If that same LAer can do a pantograph or free-hand edge to edge design for .015 per square inch, the cost to the quiltmaker is $60, so she's getting a more intricate design for only $10 more.
Hope that helps explain it a little!