The thing about this hobby is you have the upfront costs, and the ongoing costs.
As far as the upfront costs go, you can go cheaper, but it’s almost a certainty that you’ll wish you made different purchase choices. This is unavoidable and there’s nothing you can do about it. And this is irregardless of how cheap you went or how expensive you went.
Other ongoing costs are the supplies, like food, salt, test kit refills, etc. These are obvious so I won’t go into detail. But…there’s other ongoing costs that include “hype” related purchases, such as coral supplements, fancy wavemakers, cleaning gadgets, etc. etc. The industry thrives on making hobbyists think that their tank will crash and their corals won’t thrive unless you buy X, Y, and Z. The key is to keep things simple, spend your money on automation and things that make tank maintenance easier on you…which translates to you actually carrying out the maintenance. Many people lax on maintenance because it becomes more of a chore.
You mentioned an Apex, which is great, because you’re talking automation and an easier way to monitor water quality. This hobby isn’t about keeping quality fish and corals….it’s about keeping quality water. The fish and corals will thrive as a result.
The more you’re willing to invest in knowledge, automation, and quality equipment from the start will dictate how long you last in the hobby. I’d first recommend watching videos focusing on all the maintenance requirements of a reef tank. If you’re still interested after that, awesome. If you learn more ways to make maintenance easier on you…even better.