You did not say for what sort of chassis. There is probably a greater variety of resin bodies made for the original Aurora Thunderjet and the Johnny Lightning/Auto World Thunderjet 500 chassis. Snap-on type bodies for Aurora A/FX and Magnatraction chassis as well as the X-Traction chassis are not as easy to come by. Bodies that fit the latter types will usually fit Tomy Super G+ chassis if they have the wide body adapter. BRP, Road Race Replicas, MEV or Hot Laps Racin might have what you are looking for. There are a number of casters out there that do not have regular websites, they sell on eBay.
With Resin Dude you place your order first and get an e-mail advising you to send a check or use PayPal. I don't think he takes credit cards. I should get the bodies that I ordered in a few days, if there are no distractions I should have one painted and mounted on a car in a week or two. The bodies that I ordered are made for T-Jets.
I got another e-mail the day after the first one and I paid via Pay Pal. I got the bodies a couple of days ago, I would have posted sooner, but I lost track of this thread. The bodies are very high quality. They are about a perfect thickness and are without any blemish that would have to be fixed before the body was painted. The body posts have to be drilled for screws. The exhausts are molded with the body, and might sit a little low but they can easily be detached from the body and remounted. The body is a little wide, so it could also be mounted on a Tyco, Tomy or LL chassis. If you are fussy about scale width you would have to take a section out of the body. Rear bumpers are included as a seperate part. All in all it is a great deal for $10.