There was no way I could afford that within the fixed budget for this project. I did have an option, however. Zakheim recommends applying the varnish very thin. It is strong and it doesn't take much to protect, he says. Following is a recipe for making your own Soluvar-type varnish to use as a final picture varnish for murals.
Solvents are available at professional paint stores.
Acryloid resins can be ordered from businesses that supply materials to art conservators. They may be back soon. Call to find out. Metal buckets are preferable to plastic because there is a slight danger of spontaneous combustion with these ingredients in a plastic bucket. Metal buckets can be difficult to find, but some industrial paints and other materials still come packaged in them.