The cycle happens whether you try for it or not in most cases. As for spending money....the only things you HAVE TO buy are fish and the tank....however, it is good to have the testing equipment on hand even AFTER your tank is established, if for nothing else than diagnosing problems. About 75% of the time, fish deaths are either directly or indirectly related to water quality, especially for beginners. Testing often can help catch those water quality issues before they get bad enough to do harm to your tank.
No, it's not necessary to spend money, but just like any other pet, you've get back what you put in. For instance, if you have a dog, sooner or later you're going to have to take it to the vet if it's sick. If you neglect this, your dog might get ill and die from something that is easily treatable. Since this is not feasable for most fish, being able to diagnose diseases on your own is crucial to keeping your fish healthy. Water quality is usually a good place to start.
However, whatever works best for you is what you should do. I've just found that there are a few basics that almost everyone says works for them (granted, to varying degrees, some people are just luckier than others, I suppose....).
Believe me, any way I can avoid spending money, I do. There are some things I simply won't compromise on. Like I said, you get out of a hobby no more than what you're willing to put in.
