I imagine powder coating is like sign making, the more serious you want to take it, the more you need to spend. I'm guessing like my cheap chinese cutter, these cheap entry level powder guns you see at Eastwood and Harbor Freight make it look cheap and easy.
Your basic needs:
1.) Powder application equipment. The cheaper models I listed will apply powder, but with marginal success. You can skip multiple coats and faraday issues will be a nightmare. My gun application gun retailed for $1500, the top guns are $4500+
2.) Application area. A dedicated ground system is a must. Powder containment (booth) is not a need, but be prepared for a mess if you don't and any debri in the air will attract to the static charge and adhear to the part. Humidity can give you issues and your area has to be clean free of any type of silicone contaminants.
3.) A extremely clean/dry air source is a must. Think along the lines of a painters filtration set up. Any, and I mean .01 microns of oil or moisture will mess up your part.
4.) A dedicated oven. You can start with a household oven if you are only going to do small parts. Once used for powder it can no longer be used for parts. The downfall is home oven temperatures can vary 50-60 degrees. Temp needs to be held within 5 degrees normally. Ovens are expensive!
5.) Metal prep area/ sandblasting/chemical pretreatment. All metal has to be extremely clean, prepped and free of all contaminants. Out gassing is a big problem, and metals need a phosphate treatement.
6.) Chenmical strip. You will mess up, parts need to be stripped and prepped if used, and powder coating is 10x's tougher than paint and just as hard to remove..
This is the basics. I could go a lot deeper, but right now don't have the time. I need to get back to work! But this gives you the basics at least. It's not rocket science, but there are a lot of things that can go wrong. I originally thought I could get started for a few grand. I am a small shop and have over $15,ooo invested so far.