I am looking for a formula to tell me the quanity to buy given the following.
I want to buy something at 3 or more different prices. I want the average
cost as we increase in price to be $1.00 below the purchased price. I want
to know how many I have to buy to bring the average up to $1.00 below the
purchase price and continue to do this as we make the next purchases at the
next higher price we choose.

This sounds like a situation to use the solver add in. Go to Tools, addins,
and check the solver. Then set up your spreadsheet with appropriate
equations to limit the volume on your price tiers, and force the computed
average cost to the last price less $1.

"Charles" wrote:

I am looking for a formula to tell me the quanity to buy given the following.
I want to buy something at 3 or more different prices. I want the average
cost as we increase in price to be $1.00 below the purchased price. I want
to know how many I have to buy to bring the average up to $1.00 below the
purchase price and continue to do this as we make the next purchases at the
next higher price we choose.