Powder coating is an amazing and durable product if and when it is prepped for and applied properly. The two biggest problems that people commonly have with powder coating is improperly applied which is usually not baked at the appropriate temperature or for the proper length of time. The most common problem is not prepping the item to be powder coated properly and having it flake off in corners, crevasses or odd shaped areas, powder coating takes best to completely smooth surfaces which is tough to achieve. The best solution that I've come across for this dilemma is Lab-Metal which is a filler that can be used like "Bondo" but has enough aluminum in it to take the grounding for powder coating.

http://www.alvinproducts.com/Products/Products.asp?id=2

I have only ever had it done professionally.  Done that way it is AWESOME.
So far only iron and steel was done... the powder coater woud not even consider lesser metals as they acid bath the and or sand blast as part of prep.

Iron intake and iron exhaust manifold in wrinkle black
Pulleys and brackets in satin black  all on a 1965 390 V-8 engine.