What revision is it? Does it have any issues? Any accessories like music rest, original stand and case, pedals, literature?
Realistically, an asking price around 1,500 US$ seems reasonable (2,000 US$ if there is some additional stuff coming with the unit). 3,000 US$ seems more like wishful thinking -- many auctions are priced like that in order to take excessive eBay fees into account (or make people offer money and sell the unit outside eBay in order to avoid eBay fees). Also, many units sold on eBay are in dubious shape electronically so asking 3,000US$ for an instrument which is prone to break is a bit daring...
A known culprit are the SAD BBDs used with the Mk. 1 (rocker switches). If one (or several) of these fail, good luck. There are other components which do not age well, and the Mk. 2 often has an annoying "click" sound in the Human Voice section which is caused by several BBDs (MN300X in that case) interacting with each other. This fault can be fixed but you ought to bear in mind that the VP is most likely in need of some overhaul -- if fully overhauled, your friend may of course ask more for the unit.
That being siad, the VP-330 is one of my all-time favourites. Wonderful keyboard.
"Like the light from distant stars, Stephen Parsick's music has existed for some time, but is only now reaching us on Earth." -- Chuck van Zyl / Star´s End