I think you have the rifle angle covered to be honest short of something like a Henry .22
The .30-06 can be up or down loaded to hunt just about everything in North America. For smaller game you have the .223s, which can hunt everything smallish and leave you some meat. The .22 can take small birds or squirrel if need be.
You have an 870, which is a great choice. Highly useful in multiple situations.
Your pistol category is a little light, but you have this in the rifle section, so I assume you are looking for a long gun.
The Henry is a great choice. The ammo is cheap and the little one can shoot all day and not hurt himself or your pocketbook.
The lever gun in .30-30 - while really cool - would overlap what you already have other than quick follow up shots.
You could think about an AR or an AK if you were so inclined.
The AR would be more than the budget but you can find an AK in that price range pretty easy.
I guess you will know it when you see it.