Breast forms are a widely used solution for genetic males who want to have a feminine look and the Breast Form Store has a great selection of quality products. I see questions from time to time about those rubber vagina panties, but I've never heard from a satisfied purchaser. They certainly don't look realistic to me and I'm sure they're quite uncomfortable. They're expensive, too, and some are made of latex which may last about as long as a rubber band. I think for visualization purposes you'd be better off doing a bit judicious tucking and taping.
If you work on your photo editor skills a bit it's really not hard to get a pretty good idea a different appearance that way. Use your camera's remote or self timer to snap a well lit frontal pose against a plain background. The proliferation on the web of images of the female anatomy make it easy to find something that matches most any photo you have. I did that years ago. I wouldn't rate myself "10", but it was not a bad look for me.
