If you have thousands of backlinks in Google's supplemental results, will they add to your PR? Does anyone know?
Let's begin by discussing why these pages are in Supplementals. The most common reasons for ending up in Supplementals is 1) lack of incoming links and 2) duplicate content. These pages also rarely have any PR and don't show up in the SERP's. It can be months before Google ever crawls these pages again so it will be some time before you will see any real value from them. Did you purchase a sitewide link? If you did, you should know that 5,000 links from the same domain does not carry the same weight as 5,000 links from different sites.
I know that, but I have an idea as to how I can get hundreds of thousands of backlinks in supp results on good sites for very little cost. I'm wondering if it's worth it.
If these are crappy pages and will always remain in the Supplemental Index...then no it's not worth it. The main thing to take away here is that the reason they are in Supplementals is because they have little or no links pointing to them. If Google visits it once every month...what's the purpose? But if you think that these pages will eventually get out of Supplementals, and you purchase a permanent link (since it can take months to get re-indexed), it would be worth it.