If your budget permits, you can't go wrong with a kit from Kibler … I am saving for one myself (partial to his Southern Mountain Rifle). If, however, that's too much money, you can get into flint for a good bit less if you go the Thompson Center or Lyman GPR route. There are some things you should know, however. Some will tell you that these are "hawken" rifles... this is like saying that a Yugo and a Maserati are both automobiles.
The Lyman and the Thompson Center fit slightly differently, so you should try to shoot them, or at least put them to your shoulder and see the difference. Some people say they have no real preference, but some suffer 'cheek slap,' depending on your individual conformation (length of pull, drop at comb, drop at comb, etc.)
Also, the Thompson Center is no longer in production, but not to worry - there are still a huge number of them out there, and if you're halfway careful, you can score a decent used one at a fair price. The Renegade has one inch (across the flats) barrels, but their GPR uses, if I remember correctly, 15/16. I use the one inch barrels. You can get drop in barrels for .45, .50 and .54 calibers, if memory serves.
If you are looking to turn Bambi into little white packages, I would encourage you to go with a .54 (not that a .50 is bad, but I think the .54 is better - just one guy's opinion...) I have a .54 which I bought knowing that the bore was a sewer pipe, and I sent it to Bobby Hoyt and he turned it into a .62 (20 gauge) smoothie... great fun to shoot …
Many folks look down their noses at the T/C locks, but mine have never failed to function (with the exception of user error- dull flints and the like). I can't offer any guidance about Lyman, since I've never owned one, but the have a fair reputation. The notion that you have to spend a zillion dollars on a lock is incorrect, to my mind: a well tuned lock with a properly set flint will spark more that well enough to get you going if everything is properly set up).
And that's the "tricky bit:" if everything is properly set up … a good bit of the fun is in the tinkering and getting it to work: each flinter is subtly different from its brethren, and will require slight tweaks to obtain maximum performance. That's the magic: each time it goes "bang" the little voice in the back of my head says, "wow- it really works - how 'bout that."
So, to paraphrase the little green Star Wars fellow, "once rocks banged have you, forever will they dominate your range time."
Make Good Smoke!