06
.270
.7mm mag

Are all great choices . You will not see much difference inside 300 yards. As you approach 300yds the .270 and 7mm will out perform the 06 . The .270 was my favorite . The 7mm mag will give you a wider band of ammo choices. I started with the .06 and switched to a variety of calibers. The .270 was my favorite by far.

I would by a used rifle before I would by any of the new off the shelf store guns. It's not unreasonable to expect to find any of the above on the $450 range with a leupold variX of some flavor on it. A much better choice than an off the shelf package with cheap glass. Lots of people buy guns and never use them . Look for Ruger , Winchester model 70 . Rem model 700 BDL Tikka, husqvarna. To name a few.

Ask people what to look for in used rifle if you are not sure.