So I have searched google on my preferred keyword. The #2 result offers advertisement. I am in the process of finding out what it will cost (assuming I ever hear back). It is probably impossible to answer this question.. but what would a link like this be worth to you? The page my text link would appear on is framed PR5, and the front page of the site is PR6. It has about 300+ backlinks that all look like natural high quality links. Page has been around since 1996.
The only question you should be asking yourself is how much targeted traffic are you going to get from that link.
That's not what I was expecting to hear. I thought a link on an "authority" site was valuable in terms of promoting your own site with search engines? And to answer your rhetorical question, not much traffic, but extremely targeted.