Part of the problem with the WS stuff is that you can't do what's "best" for laying track with it. That is, after gluing down split cork to a centerline, for accurate curves, spiral easements etc., you then sand it lightly to get a smooth surface to lay your flex track on, using a small sanding block with 220 grit emery paper on it. My track sanding block is something I made from a straight piece of premium pine 1X3, with sloped/rounded ends, with the emery paper just wrapped tightly on it, then stapled to the top side.
Since Code55 ME flex and hand-laid Code40 PCB track follow the lumps and bumps of what you glue it to, it's important to sand your roadbed. You can't do that with WS foam roadbed.
So, cork is getting costly eh? I don't know since I stockpiled several cartons of Midwest Cork Products N Roadbed and HO roadbed and I've still got at least three cartons left. BUT, since many of the engines I run on my track cost several hundreds of dollars each, I probably wouldn't feel too bad about paying $29.95 or such for a carton of the best roadbed made to ensure my expensive, and not-so-expensive engines and costly trains run reliably and smooth as silk on the track I put down for them.
Just sayin'...
Cheerio!
Bob Gilmore