If you have difficulty holding the needles, you may also have difficulty threading a machine. Just a thought. I remember seeing posts about this knitting needle holder a while back. You might want to consider it before you take the plunge on a machine. I know for me, that's too many parts. Things tend to break down for me. I can't afford to fix them and I'm not mechanical myself. Anyway, check this link out and see what you think.
http://knittingaid.com/