Businesses aren't worth what the owner asks for them, they are worth what the buyer is willing to pay for them. If those are the same amount, you have a deal, otherwise, make an offer.
I have a related post on my blog at blog.timberry.com from January of this year and there is a related post on Anita Campbell's Small Business Trends blog from yesterday. You can also search the web for "business valuation."
Tim Berry is the chairman of Eugene, Ore.-Palo Alto Software, which produces business-planning software. He founded Bplans.com and wrote The Plan-As-You-Go Business Plan, published by Entrepreneur Press. Berry is also a co-founder of HavePresence.com, a leader in a local angel-investment group and a judge of international business-plan competitions.