After spending lots of money on Gamsol I have switched to Sunnyside Odorless Paint Thinner. It smells less than Gamsol, which is already pretty odorless, and costs about $6 less than Gamsol per gallon. Both products have less odor than Turpanoid. BTW: Turpanoid Natural is not even in the running. A horrible gooey citrus oil that never dries and is only good for stripping dried paint off tools.
Sunnyside Odorless Paint Thinner is available at Truevalue and Servicestar hardware stores but you will have to special order it. More and more art stores also carry it. I order mine from a local lumber store that deals in Sunnyside products.
http://www.sunnysidecorp.com/gold.htm