I have found out that there is no one in my area that sells black powder

Should I make the 3 hour drive one way to buy some more or do I look for a substitute?
I have a new T/C Hawken .54 that I want to begin working up loads for spring bear season, and I would really like to find something local that works in my rifle. I have been told that nothing beats the regular black powder in the traditional sidelocks like my T/C Hawken. I have know clue, so I thought I would ask for some expert advise
The big question is... your .54 caliber T/C Hawkins is it a cap lock shooting a #11 cap or a flintlock? If the rifle is a flintlock, you are doomed almost to need black Powder to shoot. If it is a cap lock or percussion lock also called, sub powders will work just fine. The two powders I would recommend is Pyrodex RS or Triple Seven 2f powder. If you hunt in extreme cold or wet, then the Pyrodex RS will ignite easier then Triple Seven but I'd hate to live on the difference.
The big thing is how you prepare the rifle before you shoot. Lets say you want to shoot
YOUR PERCUSSION CAP RIFLE...
Put some isopropyl alcohol on a patch. Not saturated, but damp. Swab the bore using short strokes from muzzle to breech. Then do the same thing with two dry patches. Now with the cleaning loading jag on, push a dry patch to the bottom of the breech. Pop a #11 cap off and pull the patch. Look for a burn mark on the patch. Don't be shocked if there is not burn mark. Some rifles take three caps to get one. If no burn mark, push that back down and do the same thing. Pull the patch and check it again. When you see the burn mark, pop one more cap off. What you have done is cleaned the bolster of any oils or gunk. Also you car boned the snail. This helps the spark from the next cap bounce down the snail into the fire hole.
Now load your Pyrodex RS or Triple Seven. Tilt the rifle lock down facing the ground, and slap the side of the lock. What your doing is knocking powder into the bolster at the end of the snail (fire channel). Seat your projectile, cap the rifle and I will bet it will fire just perfect.
If your hunting... load the same as described. But if you have a place to do this (careful not to loose your nipple), take the nipple out of the bolster. Now drizzle just a little powder down that hole. Replace your nipple. And cap it. That rifle will fire.
When your walking around in bad weather, take a tire valve stem cover, cock the rifle, put that valve stem over the percussion cap, and lower the hammer on it. That will keep that area nice and dry. Over the muzzle you can use a condom, finger cot, electrical tape, plastic wrap, to cover the end of the muzzle. Also you can shoot right through that with no loss of accuracy. It will keep rain and snow out of the end of the barrel
Making that Hawkins rifle shoot is not that hard. All you have to do is prepare them and they will shoot the sub powders, all but BlackHorn 209, off just fine. Keep your powder dry and you will be fine.
90 grains of Pyrodex RS a .015-.018 patch and a .530 ball will shoot real good I bet. If shooting Triple Seven lower that to 85 grains and try that. If your shooting maxiball, start it out at 70 grains. If you want more ideas of what to shoot, let me know.