My dad sold his 07' Blizzard 800 Ptek for $4300 when he was DESPERATE for money. His original asking price was $6000.
The 1000's are entirely different ( Even a different chassis ).
The 800 Ptek was a great, powerful, reliable motor. I've seen 2 problems with reliability on them. The first one is the needle in the carb is not adjustable, so it must be shimmed. A lot of dealers will do it for you for the price of a carb cleaning. Chances are it may have already been done. The second one is, when the rider is not careful, they die. They have a decent low-mid range, and up top they have incredible power and torque.
When my dad was debating between 2 and 4-stroke, he decided to sell his Rx-1 that he had already put an IQ skid in, upgraded the front shocks to Ryde FX shocks, raised the seat a little, put a clutch kit on it and then did some other work here and there. His first ride on the Rev he hated it. After he got the suspension dialed in, and we got a little more snow, he couldn't have been happier. He liked the positioning, the power, and the fact that at startup it didn't smoke as bad as his 4-stroke. Yes, 4-strokes are actually dirtier than you think. If you dont believe me, start a cold 4-stroke sled with a piece of paper a few inches from the exhaust, and then after a couple minutes, rev it up a few times then look at the paper.
The Rev 800 also has the SC-4 skid which is a great suspension.