There really isn't anything I know of that substitutes for Retayne. Retayne is widely available online from sources such as Dharma Trading and ProChem. Here is a link to it on Amazon:
http://www.amazon.com/Retayne-Color-...0276151&sr=8-2
Here is a really good informative article by Paula Burch. Retayne does contain a small amount of formaldehyde:
http://www.pburch.net/dyeing/FAQ/fixative.shtml