This is what I use when creating baselines for different price-points:
https://www.logicalincrements.com/
If you feel like you’ll need more RAM or a bigger SSD then that’s a simple thing to do but this will give you all of the components you need for a solid system at whatever your price point is.
That said, the “Great” range and up will play pretty much anything. You can even play pretty much any game on the “Good” range and up. So if you are looking to save money, I’d say the “Great” range will last you a good 5 years right now at least.
While Warframe is a perfect example of a well done FTP model, you can buy a lot of stuff with real money in Warframe, it isn’t just cosmetics. But it has limited PVP and the community is fairly friendly, so it isn’t so much Pay-To-Win as it is Pay-To-Not-Work-Hard.