Toyota spent millions on a frame recall. $8-10,000 isn't unreasonable. The labor is heavy. ALL parts come off the frame; engine, dog house, cab, bed, drive train, suspension, fuel system........everything. Then everything gets installed on the new frame.
A patch is just a temporary fix that may or may not hold.
Schmearing cosmoline or similar products won't help your broken frame. It may delay rust on the new frame, but that is not the immediate problem. Best path is to keep it clean and dry. Rust can not be prevented, only delayed.
Your other option is to do the work yourself. If you are a good scrounger, you may get lucky to find a reasonable frame in an auto salvage yard. Although, I wouldn't hold much confidence in the speed or success of such a search.
Frankly, your best bet is to saddle up, open the wallet, let Toyota schedule and do the frame replacement. They have done quite a few, so they are very experienced and efficient with the task.