If you want cheap wifi, you should look into the RN-XV modules:
And an xbee Explorer to do the voltage conversion for you:
You will need to put a pullup resistor on the DIN pin on the RN-XV module itself to make it work with the xbee Explorer.
These modules are not good for servers, since they can only handle 1 connection at a time, but they make great remote trancievers.