There are many ways to load for a Maynard. Check out The NSSA sight ( n-ssa.org ) If you want to shoot on the cheap there are plastic cases available which only require black powder and a bullet pushed in with the thumb. They work well. For a mold Lodgewood, and S&S sell a lee .515 which drops eather 4 or 6 at a time check with Larry for the size of bullet sizing die you should use. That is all you need to get started.
If you want to go with brass cases the suppliers above have both full, and reduced capacity ones available. For dies the outfits already mentioned here have them. To save a little you can use dies for the 56-50 Spencer by Lee and others. Of course you don't need the decapping feature, but the size and crimp dies will be helpfull. You will also need a shell holder. The British .577 holder will work, and is available from RCBS and others. You can buy custom molds or check e-bay for a lyman 515139 mold. That is the origional and dues very well. They may have re-introduced it in their current line-up
You will get many opinions as to powder, lube etc. try many and use the one that suits you. Be cure to use black powder only, and DON'T leave an air gap between the powder and bullet. Cream of Wheat is a good filler as you will find the sweet spot is around 22-27 grs. of 3 f. unless you want to shoot longer than 100 yards.
The Maynard is a great gun and fun to shoot. Many were taken west during and after the Civil War.