During frame 1 I had a vise and some straight edges, BB, HT, crown cutting tools. Other little stuff like files and tube blocks and the like.
By number 3 or 4 I had a small piece of granite, but migrated over to using Bringheli post mounted on a sheet of 1" mdf board cut into thirds and glued together. It works surprisingly well for checking, not cranking though. It was more accurate than anyone's first few frames will ever be. I used it until I got a nice cast table at a local sale. At that point I was consistent and refining. Somewhere in there I bought a Bringheli jig and still use it. I think about frame 5 or 6? A good torch, nice regulators, dynafile, what else? In the end it's a lot of regularly used little stuff that is valuable. Out side of being able to measure to a good standard and cutting/facing everything else is gravy. You can do without a lot of stuff, I don't really have anything fancy outside of the specialized cutting tools.
I would rank them:
1. torch
2. cutting/facing tools
3. surface w/height gauge and accessories
4. dynafile
5. jig