I've used one aerosol of dinitrol 4941 and It was great. However, if your thinking of doing a full car, I don't think it would be very effective. I could be wrong, but I don't think you'd get enough coverage.
If you're not going deep inside the box sections you can do a lot with one of those spray bottles with a trigger and the runnier Dinitrol products like ML3125. I have one I use for touch ups where it's not worth getting the compressor out.
It's worth getting a small compressor though. There are a lot around for under £100 that will be perfectly fine for occasional use and DIY jobs.
When I did mine I was using my mate's compressor as I was waiting for mine. I only used very low pressure so you would get away with an ultra cheap compressor. I bought a cheapo compressor just for lugging around, blowing up tyres and using with the air nailer and it only cost me £39+vat ! The compressor paint cans are better value so it would virtually pay for itself. I bought 14 cans after following their list and have about 7 left in the garage!