Today's price would be $100I took my rusty tank to a custom Harley shop where they guy was really impressed with my Cub Cadet project, and he was more than happy to tumble the tank with gravel, and silver solder the pinholes that showed up. No sealer was needed in my case. This was 15 years ago or more, but it cost about $35-40, I think. That guy was also a good contact to build. He glass bead blasted my cylinder head for a few bucks as well. It looked as nice as the day he did it on the day I sold it two years later.
Key to minimizing corrosion in the fuel tank, do not store or allow to sit between uses, without a full tank of fuel (gas or diesel). Winter storage, use a fuel shut off valve to protect lines and carb. Add fuel conditioner (I like the blue marine stuff), fill tank. When ready to use again, drain tank, add clean fuel, open shut off valve and all should be good. No oxygen - no rust. And yes fuel has oxygen in its composition. It’s not enough to support corrosion.My experience with tank sealers is that they will eventually deteriorate and flake or peel. If all you have is rusty looking sediment in your bowl, then drain the tank completely to get rid of the water that's causing the rust, flush it with some sort of solvent and dry it out with compressed air or leave it sit out in the sun with no cap on it, then blow it out again. That should get rid of the water in the tank. A little bit of surface rust on the inside will not hurt anything as long as it stays put. You still may end up with some rusty looking sediment in the bulb, that's ok, it's doing it's job and, will eventually clear up.