I recently changed my own. It wasn't that difficult, just a PITA due to all the surrounding components that had to be moved out of the way to give the pan enough clearance to come out and back in. Being a fairly inexperienced mechanic it took me a total of about 18 hours over the course of a few days. As long as you have a decent repair manual, the right equipment, and some very basic mechanic skills you should be able to do this yourself.

Then again I probably wouldn't do it by myself again, so I'd suggest finding someone in your area to at least help you throughout the repair. As for the pan itself, you can either get a new one from ECS for about $200 (what I did), try to find a used one somewhere, or just take it to a welder like Ghost said (what I would suggest).

Hope this helped, feel free to contact me with any questions. Let us know how it goes, and good luck.