Here's my story.
I bought a used summit 450 about 10 years ago. I really like the grill, but as everyone knows, they have rusted issues. On mine, the flavorizer bar supports rusted out, and I decided I was going to make replacements out of stainless steel. Well, when I took the grill apart, I saw how bad the firebox had become and I decide to rebuild it, as I had replaced the burners about 2 years ago. In the course of doing this, I decided that if I was going to spend the money, I might as well upgrade to a 650. as I had run out of room on the 450 on more than one occasion. I found one on offerup, for cheap, but it's rusty too, so I bought it for parts.
I started rebuilding it like Jon is to his project while I looked for a sheet metal fabricator locally that could make the parts. I already had some stainless sheets that I had picked up at a garage sale a few years back that were big enough to make the parts, so I just needed the labor.
I took the parts to a shop close to work, and he quoted me $300. The owner did the job himself, and it was a cash deal. All told, I've got $400 in the new firebox, and they are 18 gauge 304 Stainless steel. When it's finished, I'll probably have $600 in the grill and it will literally last 200 years. I've already told my kids that they can never sell this grill. Now I just need to find 2 more valves for LP because the 650 I bought is for natural gas and I need to convert it to propane.