going off memory, i think the 65vt60 was around $3500 'at cost' when new. like brand new had to wait for them arrive new. i want to say the 60" sold for as little as 2500 NIB near the end, but then went up again when plasmas were officially 'killed'
that all being said, there is no way the owner doesn't have a price in mind. s/he is most likely hoping you'll offer too much. i don't blame them, if you offer less they say no, if you offer too much they say yes. so, if i were you, i'd either ask them what they want, or offer a bit low. start at like 1500, with the hopes of getting it for around 2000(if in good shape). i mean, it is a couple years old, it has a fair bit of use on it, and presumably no warranty whatsoever. i've never been a believer that a product should ever increase in price, and my usual rule of thumb is 50% of new. but this tv beats the snot out of anything on the market right now that could be bought for under 4000, so personally i'd still rather overpay for an awesome tv than get a sweet deal on anything other than an oled right now.
Displays: Samsung PN64F8500/JVC X35
AVR: Pioneer VSX-1130K, 7.1/5.1.2 audio
Sources: HTPC(Enby), PS3, XBOX360, Wii
Control: Harmony One