I should add, working for a company that designs parks and playgrounds sometimes, that commercial playground equipment is expensive. My shock about the playhouse on Bob the Builder was that it was clearly being installed in someone's backyard.
Cheers to that. I don't begrudge commercial playgrounds their cost, they must be sturdy, weatherproof, safe, approved, etc. But when designing a series of small kindergarden schools, we designed our own treehouses and had a carpenter build them because the cost was just too much for a small business. (we designed and built up to code, but didn't need to have them preapproved by the govt, so that was cheaper too)