Ed, why is anyone looking to lease 10,000 square feet of space for a cell tower? You could fit 5 monopoles fully loaded with equipment cabinets side by side in a footprint that big.
Some factors to consider are your proxiity to the city, and distance from the highway. Is the carrier letting you get revenue from additional co-locating carriers? Who is the lead carrier on the cell tower lease?
I can't really throw out a number because I don't have enough information. One thing is for certain, if you don't respond quick enough to the carrier they may look elsewhere. If you need help negotiating the cell site lease fill out a contact form and we will call you.