I have found a replacement for Hareline Scudback that is identical to the original. Here are photos of the 1/4" and 1/8 " clear Hareline Scudback.
It is identical to Sew-Ology Clear Elastic that I bought in the sewing section of Hobby Lobby. See the photo of the package and the material below.
Sew-Ology and Dritz brands of clear elastic
Sew-Ology elastic 3/8" outside the package.
This is clear elastic that is in the elastic section of the sewing departments. It is used in swim wear and underwear and is sometimes called clear swim wear or bathing suit elastic. Other companies make a similar material such as the Dritz brand that I bought at Joanne's. The Sew-Ology brand is thinner and better IMHO. I bought both to examine them.
Both brands are 3/8" in width and you get 5 yards of it for about $2-3. It comes in 3/8" width, and that is why Hareline cuts that into a 1/4" and 1/8" to sell it. I plan to cut mine into the same widths using a rotary cutter on a rotary cutting board.
You can color it with a marker to get the shade you want like the olive Hareline version.