YOu are going to need a list of things to make that gun shoot reliably:
1. Properly sized percussion caps for your nipple. I don't know what you have on that gun. It may be rusty and need to be replaced. If so, replace it. take an extra nipple with your to buy your caps. #11 should work, but some of those guns used European sizing, and a 10.5 cap is what they are designed to use. Try the caps on the nipple to make sure they go on all the way and come off easily.
2. YOu need a nipple pick, and wrench, to clear the nipple between shots, and also clear the flash channel under it to the chamber of the gun. T/C makes a combination tool. Tedd Cash sells an adjustable powder measure that has a funnel attached to help get the powder in the muzzle, and at the other end has a wire attached to the screw in base, which you can use to clear that flash channel.
3. Correct ball size for your gun. Measure both the diameter of the bore across the lands, as well as the diameter of the grooves( groove diameter) to determine how deep the grooves are in your gun. The bore diameter can be used to select the correct caliber or lead ball. Usually, a .530 round ball works, but some have to use a .525. Choose the thickness of the patch based on the difference between the ball diameter and the bore diameter, and, frankly the depth of the grooves that have to be filled.
4. Use Goex FFg powder. Start shooting the round ball with 60 grains and shoot three shot groups off a bench at 25 yds, and then at 50 yds, to see what works in the gun. Go up by 5 grain increments to find an accurate load at 50 yds. Frankly most deer are shot today still at less than 50 yds. You might be one of those hunters who has to take longer shots. Once you have a good 50 yd. load, move the target back to 100 yds, and fire some groups. move up a few more 5 grain increments to determine if there is a more accurate load that shoots flatter at the 100 yd. distance. Most men who shoot .54 rifles are using 90 grains of FFg and a patched round ball of .530 diameter and a .015" prelubed patch.
There is a lot of misinformation out there( that's a nice way of telling you that people are lying to you!) about powders. You will be told that BP substitutes, like Pyrodex, the pellets, or Triple Seven, or some of the other substitute powders based on ascorbic acid forumlas are less fouling of the gun, easier to clean, or that you don't have to worry about cleaning the gun like you do with Black Powder! All of those representations are LIES! The subs are harder to light, absorb water and moisture faster, and corrode the barrels just as fast if not faster than BP. Many of the subs have to be compressed very hard to perform up to consistent expectations. Check the member services box up on top of the main page, at the bottom of the first section, for links to powder suppliers. There are several that will sell you powder and deliver it to your doorstep at reasonable prices, assuming you order several cans. The price you will pay at retail for the subs is often twice as much as you will pay for black powder.
5. Patch lube. Read through this forum and find several recipes for lube. Many start out using Wonderlube, a/k/a NL 1000, or Bore butter. Other used a combination lube and cleaning fluid like Hoppes Black powder solvent#13. They all work, but some work better in some ranges of temperatures than others. That is why there are so many home made recipes.
6.Something to carry powder into the woods, and to the range. You can use a cheap plastic funnel to pour the powder from the can into your powder measure at the range. And, you can measure powder charge out at home, and put them in film cannisters, like the plastic ones used to hole 35 mm film. There are similar containers you can pick up for next to nothing. You won't need a lot of them for a day's hunt. 5 should be more than enough.
7. Something to carry your patches and round ball in when going into the woods. I like a ball block, which is a piece of wook drilled and reamed out to hold 3-5 balls that have been patched and seated into the block. The block either is hung from your neck on a strap, or carried in a possibles bag. Again, you don't need to carry 50 round ball into the woods for a days hunt. Leave the extra balls in the factory box or bag at home, or in your car, while you are in the woods.
8. Short starter. Because of the make of gun you are shooting, you will need what is called a short starter to get the ball started down the muzzle of the barrel before you can run it down with your ramrod. You can make this, or buy one.
9. Cleaning patches. I like the 3 inch diameter flannel patches you can buy in bulk.
10. Ball pulling jag, cleaning jag, and patch pulling jag, with the proper threads to fit the ramrod you have.
11. a good, solid range rod, made of stainless steel, brass, or aircraft aluminum. This is needed in the event you forget to put powder in the barrel before loading a patched round ball. This is called " dry balling", and everyone who shoots BP does it sooner or later. And, usually more than once! Its only a matter of time before you join the club. You will find a lot of smiling faces staring back at you when youd do.
12. Possible bag to carry your stuff in the woods.
13. a Powder horn. You usually won't need a really big one, although they look very nice and very period correct. a Half a pound of powder is usually more than enough for a club shooting session, and you can always refill the powder horn from your stash of powder in the car. Most of us have range boxes we have made, or bought, to carry all the stuff we need to work on our guns. This can include properly fitted screw drivers, wrenches, needle nose pliers, etc.
14. You might want to invest in one of the CO2 devices to blow your ball and powder charge out the barrel, rather than trying to pull it out with a ball pulling jag.
15. I mentioned caps, but not how many. Buy then in lots of 1000 after you first decide which work best for your gun. You get a slightly better price, and that quantity will last you a very long time. You can also help out friends who run out. I also like to recommend that you buy some kind of CAPPING tool, which holds the caps in a container, and dispenses them in such a way that they are easily placed on the nipple before you shoot. Tedd cash sells several styles of cappers, from a straight line, to an oval shaped one, and to a tear dropped shaped one. I have the oval shaped capper and have never had any problems with it. It stays in a back pocket of my jeans at the range, and in a pocket in my possibles bag in the field.
That should get you on your way. You can use this list to compare what is being sold in those one stop shopping schemes you asked about. I doubt they measure up.