Matching zip colours is a pain in the ar... erm, neck.
There are very limited colours available for metal zips, but I don't think? you'll find them to have cotton tape... I always think of the cotton tape being the old fashioned, vintage kind.
I'm sometimes lucky to find 'odd' colour zips online at Ribbonmoon, but they're not usually known, branded names...(I always try to use YKK or Opti.)
Other than that, I sometimes (optimistically) hope to find odd colours at the market...(Brum for me.)
I suppose without the tape being cotton, they won't dye very well.
Sorry I've got no helpful suggestions for you.
Sandra.
xxx