Forbe's article Don't Leave Money on the Table discusses aging baby boomers selling their small businesses to retire. Interesting data point on the number of small business transactions done each year:
"Hard numbers on overall small-business sales aren't available, but small-business brokers believe that between 6,000 and 10,000 companies--most worth under $5 million--change hands every year in the U.S."
Also interesting is who is buying. According to the article the buyers are younger boomers and older Gen Xers leaving corporate life, often not at their choice:
"a crush of new small businesses will begin hitting the market as baby boomers approach retirement age. Among the potential buyers are thousands of laid-off corporate executives looking to take a crack at entrepreneurship."
The article has lots of good advice on the sales process.