Wow, I have never seen them sell for more than $150. They're pretty awkward and block the iron sights. Here is a set with a low opening bid.

http://www.gunbroker.com/Auction/ViewItem.aspx?Item=169014926

I must be missing something on this rifle. I've seen nicer .458's trade hands for $2.5-3K. Does this one come with $6k worth of gold dust stuffed in the barrel?