Browning 300 winmag rifle scope suggestions

Got my rifle and was shown 600 and 800 dollar scopes at the gun store.
I have been doing a lot of research and it is crazy the amount of scopes ther are.

What is really the diff between a 300 and 600 and 1800 dollar scope?

Any suggestions?


Will be hunting from 300 to 400 yard range but if SHTF a good sniper rifle as well.

Thanks