This Virtual Boy has the stand and controller, no power cord. The guy said he used to have a cord but cant find it and said when he tried to turn it on there was no display at all. It looks like its been sitting for years and has tons of dust on it. I know he has opened it because the screws are backed out and still loose.  Looking on ebay ive seen non working/for parts range from $40-$100. Knowing all of this what would be a reasonable offer?

considering its been opened up and all, I would offer around $40

I agree with $40. I'd be wrapping it up and sending it right to NES Freak for repairs, he did an awesome job on my VB

That was my exact thought when he was asking me to give him an offer. 

Yep I agree with the $40, and NES Freak. The power cord option goes into the controller which you probably knew, and there is a battery pack too I believe included normally. If there is any way you could test it for audio, that would help confirm the mobo is good etc.

Good tip there i hadnt thought about checking for audio. Thank you