OK; Rust-proofing/Undercoating?

Those of you who have been following my resto thread know what I've been up to....wire wheeled all the rust, applied Rust-Oleum 'Rust Reformer' and am in the process of applying Rust-Oleum oil-based enamel now. I was planning on applying spray-on undercoating over the enamel after it dries. So; several questions..
1) Which is the best bang for the buck? I've used Westley's before, it's OK and relatively cheap but stays tacky a while.
2) Rust-Oleum rubberized undercoating seems like a natural choice as well
3) Any other reasonably priced product out there? Cost is definitely a factor and would prefer to keep it at/under 10 bucks a can
4) I've read several threads warning NOT to use undercoating as rust can develop through pinholes, voids, etc and work unseen under the coating. Sounds kinda scary...
Most important is the factor that this car will not see snow/salt/rain again if I can possibly help it but one never knows. I would appreciate any comments and user feedback on products used and your experiences. For the record, I'm doing underside and trunk internals