Go to Harbor Freight and get one of their HVLP guns for like $60 and use it. I've sprayed Tractor Supply's BPS with one and it flowed out fine. Getting a smooth enamel job is simply a matter of thinning the paint properly and getting it on wet enough to flow out but no so wet that it runs.
Problem is you need a compressor and I'll bet you're considering the Wagner because you don't have a compressor... right?
There are several sources of information for applying automotive paint with rollers. If you have time and little money look into that.
