$50 a month doesn't leave you much for options.
Find a way to make that more. That's not enough to maintain proficiency with the 1 gun you have right now. That will buy you about 100 rounds a month, leaving nothing for range fees or targets for 1 trip a month.
Forget about buying another gun on that budget. Keep proficiency as best as you can and learn to carry the one gun you have.
Were I hard-wired into your situation...
Month 1: Single stage Lee press... probably the "Reloader" model. Cheap, and .45acp doesn't provide much friction at all. About $30. And a box of ammo to shoot once at the range if I could swing it.
Month 2: Lee carbide pistol dies. About $40. And a box of ammo to shoot once at the range if I could swing it.
Month 3: Lee auto-disk powder measure. About $35. Again, 1 box of ammo if I could swing it.
Month 4: Lee Auto-prime II. About $20. Another box of ammo for range time.
Month 5: 500 bullets from Mastercast Bullets. About $50 after shipping.
Month 6: A couple 100ct cartons of primers (~$3 each), and a pound of an efficient powder like Titegroup ($20). Time to start reloading your ammo instead. That pound of Titegroup will last for about 1500 rounds. You've already got brass, right? Been saving it, I hope.
Month 7: A brick of primers (1000 of them, about $30). Now all you have to worry about are range fees and getting more bullets when you shoot that first 500.
And so on...