I bought a Bushnell from Walmart for $40, and it works great. I'd like to buy a good scope/rings combo someday, but it works fine for now.

The more important thing I'd address is limiting your shots to 100yards.
Take a few shots at 150, to know you can hit that far out, if you have to.

It's important to locate where your deer was standing when you shot.
Tracking is tough with muzzleloaders, sometimes deer just don't bleed very well from a .44 or .45 cal bullet.