What would be the best, most cost effective way to fix this? I'm broke right now so can't afford to take it to a body shop. But I have a buddy that has a welder so I was just thinking of taking off the door catch and welding in a piece of metal over the rusted area, cleaning up all the rust first and findng a strong psection to weld to,and then bolting the door catch to that..will that work??

 

yup, that would work, just make sure you mark where the door catch is to have it in the same spot, and also, tack weld, and do spot welds until its filled in so you do not warp the hell out of it.

 

Im. No welded but ill let my buddy know to do spot welded incase he don't know already,,but thanks for input

 

I'd measure from common points as well. Something that isn't going to be effected by removal of the base metal. Measure from a few points to other parts on the catch & mark it down, so you can get it back where it belongs.
The tack/spot welding is a very good idea, especially on sheet metal... it'll look like fried bacon it you don't.

 

All fixed.. just needs some paint and it will be like new!!

 

Nice job!

 

That spot is actually hard to warp, not like a big flat area like a door skin. I've welded catches up with an arc welder before with good results but ya gotta know what ya doing.