Used sail websites.
Here are a few Josh. You can find mainsails that are close in dimension but likely any will need a trip to your local loft. Chances of a foresail are not too good unless 1) you really want a jib instead of a yankee, or 2) your loft understands yankees.You can use the Sailrite site for dimensions:http://quotesys.sailrite.com/quoting/sailkitpricing.htmBut notice that under "Old 37" that they call the staysail a "jibsail". Also note that their "yankee"(genoa) dimensions are for a 150(600 sq. ft.!!). Where their foot is 28', mine is 18'.Used:http://www.usedsails.com/http://www.minneysyachtsurplus.com/Also Related LinkNew, but inexpensive:http://www3.leesails.com/http://www.nationalsail.com/