To the best of my knowledge, all of a Vermont Casting Stove is iron. In fact, the Consolidated Dutchwest line of stoves that they took over in the early 90's are also cast iron. Only now, are any of the Dutchwest stoves offered in plate steel.
You may be able to go to a railroad yard and locate some iron plates. A neighbor of mine has a nice piece of iron sitting square in the center of his Harman Mark I so that he can burn wood. By so doing, he limits the underfire air reaching the wood, so that he can get a better burn.
In your case, it is doubtful that you will find someone with the coal kit if Vermont Castings is not able to supply the replacement parts, check Ebay or depending on where you are located, check the Chimney Sweep in Middletown, New York. I have visited there, and they have a number of used stoves and parts on hand. Seems the owner is a stove collector himself, an enjoys tinkering with many old stoves.
This link is broken, either the page no longer exists or there is some other issue like a typo.
for your local area. I imagine you can rig some plates to hold the coal in place. You can not however replace the grates if they are worn, and in the case of the Vigilant, there are 16 of them.
Hope you got your stove for a great price, as I have watched many on Ebay climb as high as $800.Considering a new stove can be had for around $1300, I'd be more inclined to the newer one, knowing all the parts and support were in place.