Door rust, need help

[STPrider]

Hi guys, when I bought my truck, body work (except paint) was done. I now have rust in my passenger door where the top hinge bolts on, and it is getting so bad the door is starting to sag. I have no experience with metal work, and was wondering what you would do to solve this. I have several parts trucks near me that I found on craigslist, should I buy a door for that piece and get it welded in? Or skip the donor door and get someone to just weld something in that will work? I would like to avoid swapping the door completely, it has shaved handles, speakers, etc. Thanks!