I've got a 16X42 IOR scope that ran around $725 or so. I don't know if they have any tactical variables in your price range or not. I can sometimes see bullet holes at 300 yards with that scope, but not at 400 or 500. I have a cheap spotting scope that is worthless for seeing holes past 200 yards.
Lots of choices in optics in that price range. IOR is the only 'expensive' scope that I've got experience with; but, Zeiss conquests and Vortex Vipers are in your range. Sightron SIII is at the upper end of your range too.
In addition to a decent scope, get a good, solid rest (sandbags, bipod & rear rest, etc.), and a decent spotting scope (better than my $149 redhead scope). After that, just start shooting and keep good records!
With respect to bases and rings: I've got relatively cheap Burris bases and rings and more expensive Seekins bases and rings. Not sure I'm good enough to see the difference between them on the target. Seems like all the serious shooters use picatinny bases. A full rail does give a bit more flexibility in mounting the scope.