You came to the right place for advice.
Welcome to the affliction.
My $0.02 is that if you think you can handle 50 then start at 40 lbs and work up. Initially, you will be working on form at shorter range and if you are like most of us, you'll want to shoot a lot, which a heavier bow won't allow without consequence.
For 300 you can purchase 2, 3, or 4 used bows at various draw weights and lengths and narrow down what you like to shoot the best.
I just picked up a 50 at 28 Western Field by Ben Pearson for 35 bucks. I put a new leather shelf on it and it shoots great.
Good luck to you,
Paul