OK, the model # and the photo doesn't match. The one Jeff posted looks like the Ramsa WR-T820B and not the WR-5820 (can't find any info on it, which makes me think there's an error somewhere). Allen, are you sure it's the right model number?

If, on the other hand, it is indeed the one pictured, then it's a pretty good one, judging by some of the write-ups I've seen. I personally would suggest you take a dynamic mic and headphones with you and test the board out thoroughly. You might also ask the guy to run some sounds through it, maybe via a CD player or something and have him demonstrate that all works and sounds good, to your liking. If it has all the inputs / outputs then it should prove to be a very capable mixer and you really can't beat local. I'd look into it more if I were you. Looks like a pretty good board, from what I've read about it. Tho the the asking price, IMO, is a bit much and you were right to put in a counter offer. The price trend, for a WR-T820B, seems to be around $500, based on
http://www.prepal.com/data/Ramsa.htm but, that it's local, it may be alright to go a few hundred more, thus your offer of 850 seems about right, IF it's indeed the mixer we're talking about and that it's fully functional and capable to run your rig. I wouldn't pay more for it.