Worth It?-Rust Proofing an older Truck?

I have a 17 year old truck in a high salt state. Although it has held up reasonable well, the rust is starting to sink its teeth in- some small spots on the body, the chrome bumpers, and some areas of moderate surface rust on the frame. I had it looked over by a trusted mechanic. He says the car is mechanically solid. And that the rust is not a safety issue as of now. He recommends me doing a "Scrape and Fluid Film." Basically, he wants to put in 3-4 hours of work scraping and applying about a gallon of fluid film, which will run $3-400. I'm acquainted with fluid film, and I know it does work well. I also trust the mechanic. I'm just a bit dubious because I think you'd need a lot more than 3 hours work to scrape down what need scraping and apply the fluid film. I don't know how much better he could do in 3-4 hours than I can with a wire brush, pressure washer, and some cans of FF. So, does anybody have experience with this and have an opinion on whether its worth $3-400. Or should I just drop 50 on some cans of FF, clean the truck off best I can, and spray it myself?