How about a 99 rupee speedrun in the 5 minute SSBB OoT demo, including spending all 50 rupees first? I can imagine that being challenging
Off the top of my head, here's how I think this route would go:
Collect 5 rupees from stepping stones
Buy 5 deku sticks from shop
5 rupees from stepping stones (10 rupees)
5 rupees from house in front (15 rupees)
5 rupees from behind house (20 rupees)
aqua forest escape, 40 rupees from Zora's River (60 rupees)
Get to Hyrule Field bridge, collect 40 rupees (99 rupee max)
rupee route maybe optimised in KF but who knows