Stupid question, looking for specific specs

So I’m looking for a 8.5 inch barrel with 1:7 twist so I can run subs and supers. My question is where can I find one I feel like I looked everywhere and $3000 is out of my price range. I won’t be running suppressed. Also I’m not well educated in putting uppers and lowers together. I’m new into rifles/ pistol rifles.. just looking for a point in the right direction.. thank you.