I used semi-gloss latex wall paint for most of my Mame cabinet. I used black Laura Ashley (from Lowes) on the front, cp, and some other areas. No priming at all, I just used a very fine foam roller. This finish turned out really well. I did several thinner coats (I tried heavy coats on a few rear panels and it didn't work NEARLY as well). It seriously looks nearly as good as a hard laminate such as formica. The only way to tell that it isn't laminate is to look at it VERY closely. Of course formica or another good laminate is going to be more durable, but this isn't a huge concern for home use.
For the sides of my Mame, I first used white primer, then used a blue American Tradition semi-gloss. I don't know if it was the brand of paint, or possibly because I primed, but this paint was MUCH harder to make look good vs. the black Laura Ashley I used. It took several coats and I never got it "perfect".
http://www.newwave.net/~flanham/wlanham/arcade/finished.jpgFor metal parts, depending on what they are. Rustoleum flat black and semigloss black work awfully well. I also tried a semi-gloss "grill paint" for (ironically) some fan grills on my VR I restored. These turned out perfect (no pictures yet). Not as durable as powder coating but since I didn't have easy/cheap access to the equipment it was out of the question for me.
For coin doors, I had great luck with a wrinkle finish I bought at an auto parts store. I had to experiment a lot to figure out the right way to get a good wrinkle. Basically, do 2 or 3 heavy coats, get it as heavy as you can without getting runs. This might mean holding it up to paint it and then laying it flat so it doesn't run while drying. Then it must be in direct, hot sunlight to get a good wrinkle. Hair dryer never worked for me but I got a pretty good effect from one of those super-hot shop lights. Give it about a week to dry fully (dry to the touch after about a day).
http://www.newwave.net/~flanham/wlanham/arcade/coindoor1.jpgAll that said... I've been using formica a lot lately, and it is much faster to apply and the end result is the best, in my opinion. I'll probably use it for any future projects. After getting the hang of it, applying it is quick and easy. The cost is worth it, particularly if you shop around for good deals. I've been buying "scraps" from a local cabinet shop. I bought a 4x4' piece of white for $17 and a 1.5x8' piece of black for $15, both used on my VR restoration. Totally worth it.
Wade