When I got my first muzzleloader, I managed to get along without most of the things on that list.
The essentials, you need powder, bullets, and caps.
The rifle's ramrod can double as a cleaning rod.
You can buy patching material at cloth stores, just avoid polyester or other synthetics.
You can measure powder with empty rifle casings, there is a whole thread in this forum about what each rifle case will hold when used as a powder measure.
Here's the link to that thread