Here's my re-written (cuz I can't find the original) cautionary tale: There are sometimes hidden costs associated with embroidery machines/attachments!
In my case, I purchased a Bernina 635 with the embroidery attachment. Having discovered that many of the designs I wanted to embroider required the Mega Hoop, I asked for one last Christmas. My wonderful family came through! When I tried to use it, though, my Bernina 635 went crazy. Nothing it did made any sense!
Eventually I took it to the dealer. Turns out the 635 can't handle the Mega Hoop without translational software ($200+) that can only run on a PC. Since I own a Mac, that would require an even larger investment! I felt (and still do) "taken."
My advice to you is to ask many questions - many more than I did! I referred you to the Embroidery Machines thread on this board because the people there can help you formulate those questions.
Best wishes!