Like has been said, stay away from the cheap brands ... even their top of the line scopes still suffer from the cheap DNA. That being said, I don't think that you need to spend a fortune to get good glass. Also, what has been said about 800yds is true ... it is a LOOOOONG way out there for most folks and for most plinking ammo. Remember that 1 MOA is ~8 inches at 800yds ... so cheap ammo that groups 2MOA in your rifle will have a spread (in still air) of ~16 inches
In your 308, you will need 20-25 MOA of adjustment to account for drop ... most scopes have a total of 50, but they usually start out at the halfway point, so that nominally leaves you with 25 for adjustment - more or less depending on how your bases line up with the bore. I'd recommend looking at the Burris Z-rings if you want to have more adjustment room ... they come with inserts that allow you to get roughly 20MOA more if you need it.
Back to the original question ... I have a Bushnell Elite 3200 that is a 10x40 (maybe it is a 10x42) with a mil-dot reticle that is a great scope. I use it on a 7mm-08 to shoot at ranges in the 750-1000yd neighborhood. The adjustment knobs are first class and the 10MOA per revolution that they give makes the counting super easy and error-free. It has always returned to zero and the image quality is great. I will buy another for my next rifle. My recollection was that it was just under $200 and it is nicer than my Leupold VXII for more $$$.
Stay safe and do you homework before you waste time trying to hit things at 800+yds ... you need to learn a bunch about ballistics, wind, altitude, and temperature if you want to make first shot hits at that range ... it is a lot of work ... more thinking and less booming ... but it really puts a smile on your face when you connect
Saands