An expensive activity that I do every so often is going to big live music concerts. I'd say I manage it once or twice a year at most, usually when an artist I really love announces a tour that includes a city I can get to.
I almost always go with the same two friends from school. We have a group chat that basically exists to keep track of ticket releases, and the moment tickets go on sale, all three of us sit at our laptops refreshing the page at the same time. The most recent one was last spring, when we travelled from Delhi to Mumbai to see a band we'd been listening to since we were teenagers.
The reason it's so expensive is that the ticket is only the beginning. Decent seats for international acts are pricey on their own, and that was before we added train fares, two nights in a hotel and meals out. Inside the venue, everything is overpriced as well; even a bottle of water costs several times what you'd pay outside. By the end of that weekend, I'd spent roughly what I'd normally spend in a whole month.
Even so, I think it's worth every rupee, and that's exactly why I only do it occasionally. Hearing songs you love played live, with thousands of people singing along around you, is a completely different feeling from listening through earphones. I just have to plan carefully and cut back on eating out for a few weeks beforehand.