Which welder...

[MercFan]

I'm thinking about purchasing a welder. Would like to stay under $400. My car has one bad spot of rust on the quarter panel that needs to be welded in. My dad's Toyota needs an exhaust pipe welded back together. Besides that, I'm going to use it on my BioDiesel project and for other small welding jobs around the house/garden.

Right now, with my limited knowledge, I'm thinking about a small MIG welder - like this one:

http://denver.craigslist.org/tls/1187217571.html

Not sure what the limitations are of a small machine like that - for example, it would be nice if the machine was capable of welding aluminum as well.

Any other recommendations of a good welder in my price range?!

Thanks,
James