Effect of PageRank on Internal Pages

Does PR flow down to internal pages?

[notbob]

I've got about 12,000 pages, none rank very high.

I am trying to build links to the pages, but find it difficult to get links to each and every page.

If I was to purchase a link on a pr6 site which is on the same topic as my site and has few outbound links, I am wondering what affect I can expect on my pages.

Would the effect be isolated to just the homepage where the purchased link will point, or will it flow to other pages as well.

Thank youA