Lots of good scopes to choose from up to $500. I do a little prairie poodle shooting and for a variable power scope, I'd want something that goes up to the 12 or 18 power range. You might consider some of the Bushnell 3200 or 4200 series, Nikon Monarch 4-16X42, and Vortex Vipers (not the Viper PST's, they're >$500).
Those are the first that come to my mind. I'm sure others will chime in with some good recommendations.
I started with a Bushnell Banner 6-18X50. Didn't really know what good glass was until I upgraded to a Nikon Buckmaster 4.5-14X40. I have two 3-9X40's on hunting rifles: a Nikon Monarch and Vortex Viper. They seem very sharp and clear to me. Of course, I've never looked through Nightforce, or Leupold Mark 4, or Schmidt & Bender glass, etc. to compare mine to.