Ok dude, 2 ways to go about it here!

First you mentioned a phone charger, no, phone chargers are around 5v output and wont power a computer fan which requires 12v output.
I use this method BUT I used my old Ipod charger which is 12v and that connects straight to the wall and straight to the fan. Easy, cheap and silent!

The other way is via PSU (power supply unit) Now, you can link multiple fans to a PSU. But a normal PSU requires a MotherBoard to be connected in order for the start button to start it.
**IMPORTANT**
In order to just use the PSU by its self you have to make a bypass jumper between two pins. NOT ALL PSU WILL BE ABLE TO DO THIS but most new ones will. (ATX - Power Supplies)
All you need is a small wire that connect to the ONLY green wire (pin) to ANY black wire (pin) they will most likely be next to each other.

Example:
http://img113.imageshack.us/img113/5...pleshitbq2.png

Once this is done, the jumper simply turns the PSU on without the need of a MotherBoard and on button.

Any q's jus ask :hippy: