Worth the splurge
Though not necessary, there are some items that, IMHO, are worth the splurge (if you have a little spend in your budget.)
A few things that will take your makerspace to the next level: robotics parts, power tools, batteries, a tool set, a low-heat glue gun, the biggest vats of glue you can find (because: slime), lumber, screws, nails, switchboards and circuits.
Of course, the more advanced you decide to get with the parts available in your makerspace, the more you may have to supervise to ensure that the kids are safely using the space. So, in our space, I put dangerous items in lockers they have to ask to use first, while most items remain accessible for them to craft whenever and however they like.