Don't use a spray paint. You will end up with something worse than what you have now.
But you can do this own your own with HVLP. The trick is getting your hands on a compressor large enough to allow you to do the job. If you have a buddy that has a large compressor you can borrow, that is half your battle. The rest is prep work, setting up a spray booth to kept particles out, ventilation, and getting an HVLP gun. The cheap Harbor Freight purple HVLP spray guns are well respected but you need to do some simple mods to them to get the best out of them. Lots of discussions on the web on interwebs about the Harbor Freight purple HVLP guns. Also, lots of DIY spray booth ideas are on the web too. Once you get to HVLP spraying something the size of a candy cab, that is like a 2 minute activity per coat. Doing that with shaker cans would take 30 minutes per coat and won't smoothly blend.
Getting a compressor, which you can use for other household chores, plus tooling and buying paint would probably cost you as much as taking it to a pro auto painter to do your cab.