Kitchen supply stores frequently stock maple butcher block boards.
William-Sonoma stocks Boos Block cutting boards here in Dallas. Boos are well made, come in a variety of sizes and are reasonable price for the quality.
I would call before driving, the William-Sonoma web site did not show the model we have locally so there may be differences in stock from city to city.
Obvious places to look is Yellow Pages and Google for suppliers near you.