This is the silkscreen method I just discovered. It's cheap and fast.
It works for both double sided and single sided PCBs.
You will need:
1. Your PCB.
2. Mirrored silkscreen printout (on glossy photo paper).
3. An iron.
Step 1: Transfer the Toner...
Take your board, And align the silkscreen printout. Now iron on it for 30-45 seconds.
Step 2: Remove the Paper
Once you have ironed it, let cool down enough that you can hold it. Now take it and put it in a bowl of water.
Let it soak for 2-3 minutes. After 2-3 minutes, Pull the paper and remove it.
Step 3: Finished!
Your PCB is finished!
Do the steps again if you are silkscreening a double-sided board.