Thoughts/Questions/Concerns? Thanks!
On more serious note, as others have stated, what you are reloading will help dictate the equipment.
"Reloading" has a lot of nuance to it. Yes, "a press" will allow you to reload a ton of things. It however might not be optimal.
For example if someone wants to shoot a ton of 9mm the stuff that is "mandatory" will be different than someone who shoots benchrest.
A lot of the time it's not even about "mandatory" but rather how to make ammo 'good enough' in the most efficient way possible.
Don't get me wrong, I like the premise of your thread. That said, a whole lot of people have spent a whole lot of money (and time) honing their process for what they do.
No two people are going to do it the exact same way. There is a lot that goes into those decisions.
Instead of trying to just make a list, try walking through YOUR process and see what makes sense to invest in.
For example in previous years I was loading a bunch of one fired military brass. At first I thought I could get by just trimming out the crimps. That idea was quickly dashed and for that swaging process a swaging tool is absolutely mandatory in my opinion. I tried doing it without the right tools and it took forever and my hands were sore for a week.
The real benefit of having a forum like this is that you can find a lot of people that are doing exactly what you want to do, only they might be a few decades ahead of you in the process.
In other words you are kind of being way too general. Pick someone and try to mimic what they are doing. If a certain part of their process doesn't fit you, don't be scared to try something else in its place.
And don't think for a minute that any of this is a once and done thing. Me reloading today vs me reloading 10 years ago looks completely different. I've changed my processes up in the quest for efficiency and effectiveness.
If you ask the right questions you can skip a lot of the whole trial and error thing. You won't skip it entirely but you can skip parts of it which will fast track you.
That being said, don't buy expensive stuff just because it's expensive. However if you can invest in a good but more expensive tool that will say cut your processing time by 20% then by all means spend the money. That said a $100 funnel will not add a bunch of efficiency to your process.
Basically though you should get rid of the idea that once you buy some stuff then you are 'done'. No no. You are just getting started. Just get ready for it now. Sooner or later if you stick around you will be buying more equipment as you learn more and/or develop new interests.