Please excuse the soap box but -- DON"T PAY THE PRICES!!!!!!!
If it's way too much, don't even respond to the ad. Nothing speaks louder than complete silence to a person's for sale ad. They will get the hint after noone inquires for 3-4 months, and hopefully then they will come down in price - the law of supply and demand does work.
Too many times I've sen people pay too much for a machine and then try to unload it 6-8 months later because the wife doesn't want or see the 'need' for 7 tractors. Now not only did you pay too much, but you have $100 worth of gas invested, and 3.5 hours on the raod, so now the resale price jumps up $250 to recoup the 'investment'.
If you figure things out like Mike showed, you should never go wrong. Even if he's off $50 on each piece, he's still ahead. You won't 'get them all', but financially you'll be ok.
Now for the other side of the coin -- pay whatever you want - it's your money. Unfotunately it does effect evryone involved in the hobby.
Soap box closed!