There does not seem to be many on eBay, and the prices are all over the place (20-200). 

I have not tested it - waiting to see if it would be worth the time / effort or not.

Looking at listed and sold I would say between $25 and $40.

There is also a few that sold near 200. What's different about those that I'm not seeing?

Microvision wasn't very well made, so most are non-functional nowadays. The screen and buttons, in particular, tend to be bad. A fully working one would obviously be worth more.

Ah.... That's what I was missing. Will test ASAP. Thank you.

This.

I had a boxed console, and many boxed / complete games. Some sealed. Couldn't get the thing to work, and potential buyers were very wary of that.

I barely got my money back when it all finally sold (and it was all bought cheaply at a thrift store).

EDIT: should add that this was back in 2012. No idea how the market has fared since then. I was in it for $25 or so, and pocketed an extra $5 after all was said and done.