Welcome to the forums.

I used a Kelty 20* bag until the thing was only a 40* bag and was so flat it was comical. I bought it for $50-60. I was in college. I needed a bag. It worked. I finally broke down and got a Western Mountaineering sleeping bag a couple of years ago. I will not regret that. It's exceptional. Pricey, but I never have to worry and it will last for years and years. Do what you have to to get yourself out on the trail. Stay warm and be safe. In 10 years you will not think of what sleeping bag you used. You will wish you had gone on more trips. Gear is only a means to an end.

Same thing goes with clothing. Use what you have. If you have money to spend on something, get the best that you can. Otherwise, make do. Others have suggested thrift stores and such. Those are fine. I do see that you have been doing your fair share of research. I tip my hat to you.

Another option that I don't recall if someone mentioned or not. Make your own. You need some rain pants... make some. You'll learn a new skill, customize your gear and be more satisfied with a sense of accomplishment.

Good luck and welcome to the club.
I always forget and make it more complicated than it needs to be...it's just walking.