depends on what you want it to do.
I have a vortex that i got for about $400. Killed a deer at 638 yrds with it.
I've hit metals plates out to 1000 yards. Much beyond that and the scope maxes out.
I'm actually doing a gun build right now and will probably get the Huskemaw 5x20 Blue Diamond, it runs about $1500. But I'm told it's way better than the Vortex.
Figure out what you want your gun and scope to do and then go from there. If you are just going to hunt, and occasionally shoot some long range, I'd bet the Vortex will do everything you want, and you'll save quite a bit of money.
If you want more precision, do some competitions and whatnot, you'll probably need something more.