I got 610 in the Mercenary shooting range after about 3 tries. I didn't know you got points for shooting crows and stuff though... I'm going to go back tonight and see if I can get a higher score. I'm a little disappointed that there aren't more prizes available for getting higher scores though.
Edit 1: I did The Wheel of Misfortune in the expansion pack finally. It was pretty cool I suppose, but it lacks challenge for a fully developed character. I completed it without getting hit my first time and got a score of 1,404,685.
Reaver's score in that game is 90,000... so I figure that they expected The Wheel of Misfortune to be a lot harder than it actually is. They should have created more powerful monsters for this game, as they all get too easy to defeat once you get upgrades 4-5 on magic, ranged or melee.
Edit 2: Alright, I tried the Mercenary Shooting range a few more times. I managed to get 635 but I can't seem to get any higher than that... looks like that's about as high as I can go.
I imagine that a true pro might be able to get 650-700, but that would require very high reflexes and precision cursor positioning. I might keep practicing more to see if I can get a score like that.