I know LiPos can seem daunting to start, but once you get past a few basics, it really is not too bad. Here are a couple of links to get your started:
https://rogershobbycenter.com/lipoguide/
Lipo basics - TJinTech
As you point out, to get started, you will need a balancing charger and a battery tester. There are a lot of options out there, but it depends on how much power you will need in your applications. Low power set-ups (under 750 - 1,000 watts) can be quite affordable, but price starts to go up quickly if you need higher power.
LiPo batteries have come way down in price. I have been buying
Admiral batteries from Motion RC lately (but there really are many good options). Don't get too hung up on the battery specs to start (in particular "C" rating). Again, what you need to focus on is how much power do you need to deliver. That will help you select the battery that best suits your needs.
Finally, I strongly recommend using eCalc (
https://www.ecalc.ch/) as a quick way to virtually experiment with battery, motor, esc, prop/rotor combinations. You plug in your specific setup and can see how all the components work together and what happens when you change one.
Do you have a specific application in mind? That would help point you at specific options that will meet your needs without either buying too little and having to re-invest or spending too much on a setup that exceeds your needs.