The 503 and the 403 are my favorite go to machines. I like them better than the 401 - if you have all the cams they do more than the 401 - you can select the stitch width and needle setting - right - center - left
http://www.quiltingboard.com/main-f1...s-t160607.html I don't know if that will be of any use to you or not.
BTW - that is a good price
For FM I like the old Japanese 15s.