Buying to me means giving something up, usually money, for something I need or want. So to me there are great tradeoffs between what I'll pay for what I want. My Dad used to say I made pennies scream.
Stihl 021 - I bought NEW - YEARS ago, needed it NOW.
Efco 3600 - I bought new, I didn't need it, it was new w/ warranty marked $220 at Northern Tools. But they were closing out that model, so they marked it down to $99, and then a Managers sale came along and reduced it to $50 and the guy threw in an extra chain.
JD CS 62 - I bought raffle tickets to help donate money to litefoot's brother, who had had a stroke. My wife was just recovering from a stroke. The saw was basically new
http://www.arboristsite.com/showthread.php?t=109333
/edit - and I did have to replace the rope on the #1 660, cost about a buck or less.
#1 Stihl 660 - Ebay- after a lot of research on both saws and sellers, bought used $511.
#2 Stihl 660 - the other raffle saw, redlinefever decided he was going to sell it after he got it Snellerized bought thru here $700.
So in summary - Buying used you should get a significant discount off new but you can be gambling with savings versus expenses. And you should include your time in expenses. If I have to spend 10 hours getting the best price on something that's worth several hundred to me. I had to do that with the #1 660. The other saws were instant decisions.
As my first "bigger" saw I wasn't sure how well I could handle a 660 and if it was worth it. I KNEW if I bought a used 660 I could probably sell it for about what I paid. However, I was hesitant about dropping over $1K on a saw and then having to sell it for $600.
If you research both the saw and seller you should do well on a used 660.
But don't necessarily "trust" members here either, there have been some major threads about members trying to pull a quick one on someone else.
Bottom line if you want piece of mind buy new. If you want more toys for the same $$ search, research, and buy used. The saws in my sig, except for the 021, cost me about $1260. A little more than 1 new 660.
good luck and MERRY CHRISTMAS!!