Here is some things to consider or research further
IMO the bowl needs immediate repair but unless the lid handle is coming loose the lid appears still usable. Some paint work on the rust spots might help.
I see people posting about using products like JB weld for metal repair, i don't know if it would work in this situation but there are much more experienced people who would know if you research it.
If you haven't already, i would post and check out:
http://weberkettleclub.com/forums/member-sales-trades/
I often see people posting lids and bowls that are left over from projects and there are some people over there, that have done some amazing restorations.
I would also check CL like some of the prior posters said. If you have gas assist, you will need to find a gas assist performer bowl so it has the burner holes and the cart brackets. if yours doesn't have the gas assist, any performer bowl, or older single table style One Touch Platimum bowl should fit.
If this project is a task of special sentimental value and you are willing to spend money you can purchase the bowl and lid from Weber directly. Tell the CS rep your story, maybe they can help you out in some other fashion (discount, parts from a return) who knows.
Good Luck, keep us posted.