I also thought $700 was high, but remember he is in Canada. I don't know what the prices are like there.
That said, I don't think this gun is going to be all that rare. The reason I say this is I've never looked for one, and don't know much about them, but I've seen several for sale in .280, and all of them have been $400-450 US dollars. While it doesn't seem to be as common as a Remington 700, there doesn't seem to be a shortage of them either, unless they are all just in this area.