I'm sorry you broke your lens! That bites! I really like Katrina's suggestion about setting up a "mini session" day. You could get a backdrop ready, some props (if needed), and invite over a few families to do portraits. Even if you only charge $50 or $75, you will get started and get used to charging, and then next time you can charge more.
Once you do it a few times, your confidence really grows and it gets fun. I encourage you to try it!
I love taking portraits and I enjoy the challenge of improving my work each time. I also learn more and improve my on-my-feet skills at each shoot. I think you should do it!
About paying for the lens...what about renting the 50mm f/1.4 or another one you love to actually DO the for-money-sessions....then you can BUY it later once you make the money? Just a thought!