Frankly myself I work for a distributor of paint and body shop equipment and when we can get the end user to use the better lines of paint they get better results as the better stuff covers better..does not have as much shrinkage problems..easier to work with..just a better deal ..And they do wind up saving money by needing less material..
We do carry some value lines for the ole guys that know exactly what they like and want to use..
I do not do online sales as we have found it preferable to be able to "be there" for our customers..And this is not an ad for services!!
Now on this particular truck without seeing it I would recommend giving it a severe scrubbing with a wax and grease remover..then sanding it out..doing any metal work that is needed..then prime and paint..I would not try to remove all the paint to bare metal..do that in the places where it is needed for reasons of rust or metal repair..
A lot of the guys do most of this by hand and only have a small compressor..kind of primitive compared to what is in major collision shops but given that they so some very nice work..
Now these are the guys who do read Instructions and follow recommendations as to how to do the job..
Some of these guys put out show winning jobs just because they pay attention to detail..
I have tried most all of it and now do what is known to work..