In addition to what others have already posted:
Bench vises
Reciprocating saw(Sawzall) - With the proper blade, can cut anything you would use on your robot, however it can be a bit inaccurate due to vibrations. A jigsaw is better for thinner material and/or more precision.
If you (intend to)use a lot of wood, maybe get a circular saw. There are also
metal cutting versions for sheet metal.
I've heard oscillating multi-tools are pretty versatile and useful, but I have yet to use one myself. I would definitely consider it, though.
As Joe said above, Allen/hex keys. A lot of them. You'll be surprised how often they go missing.
Another push for cordless drills. Get a few and at least the same number of batteries. They'll be in use 90-100% of the time during build season. Also sets of drill bits; they'll go missing or break, and having duplicates allows two or more people to drill identical holes simultaneously.
That's all I can think of for now. If you're okay with used tools(in good, safe condition of course), try
estate sales. You can also get good deals online at
Caring Transitions Online Auctions(the tool category is on the left sidebar.) I often see bandsaws, drill presses, and tons of hand tools there. Just be aware that air compressors/tanks and fire extinguishers should be purchased new. Air tanks rust, posing an explosion risk. Fire extinguishers experience a similar effect, and will lose pressure over time. Rechargeable ones can be repaired, but you might end up spending more to fix it than you would for a new one.
Best of luck to you and your team!