The cost of batteries is hard to get around with any of the reputable brands.
I have an M18 hammer drill too. I got it with one battery, charger and carrying bag on Kijiji for $100. The guy was asking $120, which I was going to happily pay, but he handed $20 back after I we got chatting and I told him my third son was on the way.
That was over a year ago. I used it for heavily for my basement bathroom renovation. I don't have an XC battery, which I wish I did. It doesn't last long when using the hammer.
I've been keeping my eye out for a dead battery that I can rebuild.