I wouldn't be surprised if the LAer charged more for a large quilt. The quilt still has to be loaded onto the longarm, and kept square while basting, and that takes some time. If the LA doesn't have an option for making extra long basting stitches, then it's a pain to manually needle up-down all over it. OTOH, if she uses water soluble thread (in bobbin and on top) then it's easier to stitch on the LA, and easier for you to remove later, but some LAs are not happy with that type of thread, it costs more, and might have to be ordered if the LAer doesn't already have it. I do use water soluble thread (Vanish from Superior) in my Innova when I want to stabilize a quilt without making permanent stitches, but I need to go slower than usual to keep it from breaking.