I can't afford to send mine out but I've heard of prices like this. If there was a chance the price would need to be adjusted it should of been disclosed in advance. If they knew in advance they'd be doing the binding it should of been included in the price given. Alot of people do thier own on a regular machine. It is easier if you have a larger throat machine but not necessary. I'm sending you a link for a great site that has videos on doing it on a reqular machine that might help your wife out learning to do it. You can also google machine quilting and there are lots of tutorials on youtube that will also help you out. The link I'm sending you has lots of videos and even sell cd's to help you learn.
http://www.daystyledesigns.com