Both of the above solutions are coming to about 5K. In todays computer parts value that's just too much. Want to get something cheaper then that. I have options of wifi dongles which are from 1K to 1.5K but 100% surety of working on Mountain Lion(10.8) is not there.
No that's not me but I found a way. I managed to get my Ethernet working in mountain lion. Then I configured my wifi router as a repeater bridge and connected it physically to my Ethernet which in turn made my Ethernet act as wifi.