Cost: ~$2 per application when bought in bulk
Duration: 1-6 weeks (natural red color), 2-10 days (other colors)
Ease of application: Easy with a stencil, more difficult without one.
Here's another good thing for outer game or peacocking - Henna Tattoos. I used to get labeled as a "nice guy" so I started going out with these. Nice guys don't have tattoos generally, plus you can make up stories for each one. If you get them done well, nobody would ever know that they're temporary.
You can buy "cones" of henna (you draw with the tip of the cone like it's a pen) for about $7 in a variety of colors. Natural (red) henna tattoos last for weeks, and other colors last for days. Each cone is enough for 20-30 small tattoos.
You can buy stick-on stencils if you're not comfortable with drawing freehand on yourself. They're less than a dollar each, and make basic designs (i.e., no very fine lines) trivial. If you're an artistic type and careful you could also freehand something. The darkness of the coloring depends on how long you leave the paste (what comes out of the cones I described above) on your skin, so even if you mess up you can start over safely.


Great for outer game. I have an extremely artistic friend who gave me a tattoo on my wrist that made it look as if I had ooze dripping out of my watch and all over my left hand, and a sleeve of flames on my right hand. I can't emphasize enough how many people approached me (guys and girls) to talk to me about them. I wish I could recreate them, but I'm not nearly artistic as my friend.
Here are some good sites for more information on henna tattos.
Information
Henna FAQ: http://www.henna-tattoos-kits.com/henna-tattoo/faq.htm
Stores
Henna King
Natural Chroma - Buy henna PENS here... I have not tried this, but looks easy
HennaTattoos.com - These guys sell a very good BLACK henna ink that lasts 10-15 days
Natural henna is this color

when it's first applied, and this color

when it starts to fade.
Here's what actually applying the tattoo will look like

.
You will wipe the excess gel off after a few hours.
It's worth noting that although these are temorary tattoos, they don't wash off easily. Plan on letting them fade over the course of several showers on several days instead of scrubbing them off after getting back from sarging. (i.e., don't put shit on your face on friday and expect to be able to look normal at work on monday).