I find if you practice proper maintenance, even a cheap machine will go pretty far. My mom bought me my first sewing machine several years ago (ie she cut me a check for $120 and I bought a cheap Singer for $100 at WalMart) and it still sings along after sewing fur, leather and denim. After each major project, I take it apart, oil all the parts I can get to and brush and/or blow out all the lint in the machine.
I may move on to a more expensive machine in the future (because I want to do fancier stuff), but for now I have a really good machine.
One of the most basic rules for survival on any planet is never to upset someone wearing black leather. (This is why protesters against the wearing of animal skins by humans unaccountably fail to throw their paint over Hell's Angels.) -- Terry Pratchett