Hey, I'm biased, but both powdercoating and painting yourself are great options depending on what your skills and time are. Powder is a good option for guys that don't have the ability to paint themselves, don't have the time, or don't want to fool with it. As Don says, it not really much more most times than just buying the material. Many times its less if you are looking to do a metallic or candy color. If you figure in your time for the prep and such, its a pretty good deal. We charge about $250 to $300 + blasting (about $100) to powder a hot rod frame.
The advantage to powdercoat (beyond the fact that you don;t have to do the dirty work), is that it is fully cured when it is done. With any regular paint, the solvent is curing for months and even years which means that it is not fully cured for a long time. (this makes re-assembly a bit trickier -ask me how I know!). With powder, there is no solvent and it is fully cured when it cools down from the oven. This makes it super durable. If you want even more durable finishes, powder is offered in several formulas and even super tough and chemical resistant epoxies. Dobn;t forget that for only a few $$ more you can add a powder clear coat for even more protection.
My '27 is painted body color with a 2- stage DuPont Hot Hues color and if I figured out how much time and $$ I have in just the frame and suspension pieces painted, I'd probably cry. Now, powder is probably not appropriate for my frame as it was meant to be the same exact color and blend into the body. If it were to be a contrasting color, I powdercoat it in a heartbeat. The '23 we are currently building will have the frame and suspension pieces powdercoated in Silver metallic with a clearcoat.
We just got in a nice '27 frame Saturday to be powdered in Super Gloss Black. I'll get come pics of it and post when its done.