To elaborate, the kit is almost completely reusable and quite cheap. The cards can be as simple as paper folded with writing on them. The bandages come in big rolls that are a few dollars and I would imagine last a whole season, if not more. Most of the other stuff is improvised and cheap and I'd say at least 80% of the kit is reusable.
The IV is just one of those juice bottles. It's empty and has a small rubber tube coming out of it. You just have to hold it to the casualty's arm for 3 minutes. The point is to get the medic involved and vulnerable. You can't move too much with one of those and 3 minutes is a lot of time.
It's not a terribly complicated system. It really only requires the medic to be knowledgeable and I played the medic at only my second milsim with no issues.