Welcome Marc and thank you for the great introduction! It gave me all the right kind of feels! When you build a costume yourself - you usually don't need to spend an unrealistic amount of money, and it sounds like you really want to do it!
To start with, we can just take a look where we are... The FISD! One of the best places I know of - such a nerdy, helpful, active, engaging and rewarding place to be!
Some people drag the build process out over some years and others do it in just a few weeks. There is only one way and that is your own way, and which ever way you choose, we will be here for you! Getting into the whole progress sharing with the community is such a quick flow to get into as you've already started by making this post! And thank you for that!
If you would get to the point of starting to build an armor, everything would be asked and answered in a build thread and the ball would be rolling onwards after that!
Regarding what armors to get, in the Swedish Garrison at least, it is pretty much split 50/50 between RS and TM (Troopermaster), and we have at least one SDS armor that I know of but we do not recommend those kits, as will the people buying those kits tell you since they have to do much extra work to get approved.
Just to get a taste of what you would eventually be getting into:
Imagine that you finally get to kick the legs up onto the couch at home after hours upon hours of waving, high fives, fist bumps, dancing, marching, taking images with people, feeling like a celebrity, people giving compliments on your armor thinking you look sooo cool, hearing sad stories and feeling great at heart after you realize you've made their day, collecting money for charity, meeting new friends that are just as passionate and nerdy as you are, sharing tips and helping troopers, put someone's shoulder bell on and be loved forever, getting compliments on your armor by troopers, and in the end knowing you have stood on a row as 1 of 10 TK's that has made a crowd speechless.
This is currently what I'm thinking about as I've just arrived back home from a troop! I'm looking forward to follow your thought process and journey!
Welcome to the FISD and initiating the first steps of one day hopefully becoming a TK!