Might Buy a Desktop. Looking for Obvious Signs of Malfunction

[fooloof]

Hello,
this would be my first real synth. I know nothing about synthesis and have never even used a Virus. However, from a lot of research, it seems that a Virus will suit my needs. The TI desktop is what I am after. A guy is selling one for $1500, which doesn't seem overly expensive from what I've seen. I'd probably offer him $1200 if everything looks right. So, I have two questions:

What do you think is a good price? I think the 12-15 hundred range is consistent with what I've seen elsewhere.

Are there any quick things to check while inspecting it? Obviously, I will turn it on and scroll through some patches and check for physical damage, etc. But I don't know of anything else. Could there realistically be internal problems (polyphony, arpeggiation, etc.) that can't be detected? Thanks.