First, this is hands down the easiest project in the world. I did very little investigating beforehand, and just kinda went for it. Here is what I did and some tips for picking out the right kind of mug.
I bought dishwasher and microwave safe mugs from Target. They were $5.99, but I wanted a porcelain mug so I could use the sharpie method. If you pick up cheap ceramic mugs you'll need to get a ceramic paint pin.
The boyfriend and I wrote messages on each others mugs with a regular sharpie. It was very easy to write on the porcelain. We placed them on a cookie sheet in the oven (350) for about 45 minutes. Then we let them cool and didn't mess with them for about 24 hours. This morning I was pretty nervous to wash them, but they did great. Nothing came off and now I'm drinking a homemade chai tea latte out of mine.
Highly recommend this DIY project. So many possibilities. Leave me a link if you tried a different method :)