just guessing, I'd think it costs about 10 times long arming does
Diane Gaudenski's have always been done by domestic machines, take a look
https://www.google.com/search?q=dian...w=1366&bih=643
so it would probably depend on what you wanted done. Even straight lines take more time on domestic vs. long arm, simply because you have to stop to shift the quilt sandwich all the time.
My various long arm quilters have charged me 160 to 200 dollars for quilting queen sized quilts. I make the cost count by quilting two tops at the same time, one front and one back.