I have a Yashica ML 50/1.9 lens in Contax mount - I just pulled it out of my dry box and found it to be broken. When I originally bought it (for around $30) the plastic thingy to lock it was missing, so any over-zealous focusing would pop it right off the camera. Today I found some more pieces have broken off, and now it won't even stay in its mount

I'm wondering if a repair is worth the money - I'm guessing it would cost more than $50 (if even possible.) The glass itself is in great condition however (no scratches, fogging or mold.) I suppose I could try lighting cigarettes with it on sunny days