YaD nailed it. You have to be more specific.
If you want smallish deer and are a very good shot and your state allows it and you are only interested in 100 to 150 yards shots, and you used the right bullets with the right twist *deep breath* then you can even hunt with the .223/5.56.
You want bigger critters and/or more certain/longer shots, then you can use a 6.8/6.5 upper.
You want even bigger critters; then you have the .458 socom or the .50 Beowulf uppers. My friend and I joke about these being “indirect fire” weapons.
You won’t be able to put a “.308 win” (7.62 NATO) upper on an AR-15 lower. Two different animals.
If you are looking to go the cheapest route, you MAY be able to spend less short term with an AR-15 and getting one of the more manly uppers.
But a plain-Jane AR-15 for HD and adding a base model M1A may be on par once you figure in ammo availability and cost.
If you are dead set on a semi-auto for hunting (which I am so I understand), then you are probably booting the most economical choice which is an AR-15 for plinking and social work and a bolt action for hunting. No my style, so I’m willing to spend a bit extra for the shame of hunting with an EBR.
Please see the the last line of my sig for the truth about AR-15's and being "economical"