My crown was made out of materials bought during the Liberacicus Mk II project.
My belt is from a reel of really beautiful trim I've been "saving" for a project for nearly 10 years.
Our group's "Lady of the Lake" costume was finished with more fabric and a couple of old jeweled pins from the stash.
I did have to buy the inkjet fabric to do the heraldry and the name labels for the backs.
We (bovil and I, and brittunculus and J.) bought some colored bias tape for our surcoats.
Most of the other surcoats, however, are edged with black bias tape that we had (unfolded) on a reel in our stash. One of Sunday's early chores was folding and pressing it.
(It turned out VERY narrow, and sewing it on proved to be the major bottleneck in the project. The final four surcoats were simply edged by loading a serger with black thread and doing a two-thread overlock on them. We'd all run out of the patience and coordination to feed the skinny bias tape through a machine properly any more).
'Bout time we did a costume from stash, and managing 20 of them is a good thing!