Modifications are typically specific to the brand of machine you have. There is currently a mod in that price range available for the Voyager 17. I have not seen any mods available for the QueenQuilter.
Edit: Okay, I found the people who do the mods on the Voyager. Turns out they have mods for quite a few machines, including the QueenQuilter. These people, the Dekkers, get very good reviews from the Voyager customers who have gotten mods from them, and they have one or more Youtube videos. I don't know if they are in CA, but here is their website:
http://www.dekktoutquiltingsupply.com/DOQS.html