I have seen them advertised on E-Bay. The sellers usually claim (probably falsely) that their decals are "genuine". More likely, they are modern reproductions. However, a repro decal would like nice on a restored bike, if it is well made.
I pieced together a set of Sting Ray decals on ebay recently. I saw a few Varsity decals in the process. The ones I got are indeed original. The paper and decals are somewhat yellowed and brittle. A company called hyperformance makes reproduction Sting Ray decals (the fork darts and seat tube decals are the same so these would work). I'd watch ebay.