Everything is relative, but, I think this is a fairly inexpensive hobby, unless you really go nuts.
For quality equipment, you can find stuff on a pretty good budget now days, especially with the help of a forum like this.
And if money is tight for a while, it's a hobby where you don't need to spend a bunch to keep it going. You can just enjoy some music and movies with what you have, tinker with speaker placement, settings or cables... It's kind of fun and stress-free to look forward to what you'll do next, or thing about the next little tweak.
The other nice thing about it is that a lot of equipment doesn't date itself quickly. Video and multi-channel processing does a bit (although less so lately), but a good two channel processor from 10 years ago is still good today. A good amplifier doesn't really date itself either, sure they have gotten more efficient, but, the iron stuff still works great. And speakers, well, a good speaker from a decade ago is still a good speaker today.
Also, the used market for high-quality speakers isn't too bad. The stuff moves, can be sold without involving a broker.