RPI0-need recommendation for mouse

Hello,
I am dealing with a repetitive strain injury in my wrist. I read
about trackball mice that are supposed to be a lot better for the
wrist. I was just going to go on amazon and buy one but there were so
many! So I got the idea to find a newsgroup that deals with
repetitive strain injuries and see if someone could recommend one for
me. I don't have carpel tunnel syndrome. The injury is entirely from
using the mouse. I know that prices for trackball mice range
greatly. I want a good one but I don't want a really expensive one
either. Can someone recommend one for me?

Also, I went to Staples today to look for a wrist rest to put in front
of the mousepad. They had them but they also had something called
Ergo-mat which is a memory foam mouse mat. Has anybody tried this and
if so, does it help put your wrist in the right position?

Thanks in advance for any help!
-Tracy