CFM's are the important thing when buying a compressor for HVLP. I think you're gonna want something like 10-14 cfm@40psi. Do you have an HVLP gun? Check the cfm requirements for whichever gun you have or buy. The basic 120v, 20 gallon compressor is gonna be a pain for such duty but I've heard people saying that it's doable.
I bought a Harbor Freight 60 gallon, 2 stage for around $750ish after tax about 5 years ago. I added a 20 gallon tank as a water catch; it also adds to my air capacity a little bit. Also, I used an after cooler and copper pipe as a water trap. There are many options for dry air.
Expect to pay another few hundred to setup electrical and whatever you're gonna use for drying or cooling.
Do you have a 220v connection? Can you do your own electrical? Expect to spend around $100 just for wire and another $40 for boxes and a breaker. I did my own electrical work but I can tell you that my electrician bills himself out @ $150 an hour.
You may want to consider an HVLP Turbine. They are basically a tankless compressor dedicated to spraying paint and run on 120v; I don't know if that's an accurate description but close enough. IIRC, they go for $400-800. If you're not gonna do anything else with a compressor then it's a reasonable choice.
Other than HVLP, media blaster or filling tires I don't use my compressor for much. I prefer wired electrical and battery power for most of my tools.