I volunteer at something simialir.
Any tool that’s usually bought on the cheap doesn’t last. Especially if your putting force thought it. Eg. Chain whips, cassette removers, cone spanners BB tools…..etc…. Buy decent branded versions of these types of tools and more importantly makes sure your volunteers know how to use them correctly as even good kit is wrecked when not looked after.
For 90% of the type of bikes we work on I use , my own allen keys and a knippex spanner then the shops cones spanners, cassette and bb tools and occasionaly a 4th hand tool.
Some good 15mm spanners would be good as these are used a lot as well.
I’d say buy individually rather than a specific set as you’ll get more of what you’ll actually need.