Rear Wheel Well Rust Repair

I spent quite some time searchbaring this topic so please forgive me if its been posted a million times.

I have the typical serious rust action going on with my rear fenders. I did a little bondo action and it lasted for about a year but the rust is really bad again. This time I want to do it right, cut out the rusted metal, and weld in a new piece. I know you can buy the pieces to weld in but I cant seem to find what im looking for online.
The piece im referring to is in this video at about 1:15

Proper automotive rust repair - YouTube

Proper automotive rust repair - YouTube

ALso, I dont own any welding equipment so what am I gonna need to buy in order to do this project successfully?

Thanks guys

That is one of the spots I am waiting to go out on me. I would suggest getting the piece, and if you know anyone in a body shop have then seam weld it back in for you.

That's a quarter panel sectioned for the dog leg, he must know somebody if he got that for 50 bucks, the full quarter panel is around $400, look up LKQ on the internet, they may have links to get new aftermarket quarter panels for half of what am oem part costs, but be warned about aftermarket bodyparts, they may not have the perfect fit up or the lines might not match completely.

To do auto body rust repair you'll need a good wire feed MIG welder. Preferably a Miller Hobart or Lincoln mig but I have a Northern Tool 135 mig and she does the job great. Reason being is the adjustability of the voltage. With thin sheet metal its very easy to burn right through what your trying to weld. Also when your installing the patch panel work around the panel with spot welds don't try to lay down a full bead, you will burn through. Basically you need a welder, weldable primer, seam sealer and cutting and shaping tools and the very important spot weld bit. This allows you to cut out the factory spot welds as well as create new ones. You could try your local junk yards for panels if no rust free ones can be found the aftermarket quarters will work just find but some finesse might be needed.

To kind of hijack this thread - what can be done to prevent that spot from getting rusty? My car is completely rust free but I noticed there was a lot of dirt and sand packed in part of a front fender and figured there are other parts that could potentially have corrosive materials behind them. I don't live near salt water or drive on salted roads

POR 15 is a great thing for rust prevention and stopping rust that has started.

I just tackled the rear 1/4 panel rust on my wagon a few weeks back. I used that on the bare metal, then patched it. Did that juuust in case there was any slight rust left.