Posted By:
Chris CathcartJulian,
I have a PSA 4 of it, but I'm pretty attached to it. But just about any card is "for sale" if the price is right. 
(I do think, based on recent market activity, that the SMR is off by quite a bit at various price levels. Based on recent sales, the price structure looks more like 2x the price of a '52 Topps Mantle for the most part. That might overprice things somewhat [10-20%] in the grades below PSA 7, but it would be closer to the market than what the SMR says now.)
Chris