First off welcome to the forum. It is great to have you here.
Before you pick your muzzleloader out, know the laws that pertain to muzzleloading in your State. Are scopes allowed? Are certain powders forbidden? What about the ignition system restrictions? Some States or States you might want to hunt, do not allow 209 ignition, closed breech, etc. And last consider what you want to spend. Spending a little more now, might save you a lot of headache later.
There are some good inexpensive rifles out there that will do the job for the one week a year hunter that shoots out to 100 yards. Almost any rifle will do that with practice. Then there are the mid range rifles that can have a nicer fit, better sights, perhaps other little things that appeal to you like ignition, stock design, etc. If money is not the issue then the sky is the limit.
If I had $300.00 to spend. And wanted a rifle that would do it all. I would look at a Knight Rolling Block, Some of the older Knight rifles on auction sites, and some of the Thompson Center lines of rifles. They have out of the box guaranteed accuracy (although some people claim they do not shoot well for them), great customer service, and tech support for getting load help, or just you have some questions about the rifle. Also most of them will handle magnum charges if that is your thing. Although magnum charges are not as important as you might find out and later learn.
The big thing is know what is legal, what you want to spend, and then start looking at rifles. If you find one that interests you, let us know and we will tell you whether we have good experiences, bad experiences, etc..
Until then, keep looking at them, handle them if possible and see what fits and appeals to you. Then look in your wallet and see if it is possible, and then tell us what you decided on.. Good luck in your search.