In terms of scopes in the set-and-forget category, one that'll hold zero through normal field conditions and overall be reliable, I've had good luck with:
Burris Fullfield (II & E1)
Anything SWFA
Trijicon Huron/Credo
Maven RS.2
With burris being the lower end of your budget and maven being slightly above. Also been hearing good things about Sightron S1 but have no personal experience with them.