The cheapest I've ever seen one for sale second hand was in the mid £900 bracket. I've not seen many people talking about them for a while, mainly due to how good the Sigma 50mm 1.4 is for a fraction of the cost. I've even seen a lot of people say they prefer the 1.4 over the 1.2, but that's personal taste.
Money no option, then maybe get the 1.2 but personally I'd highly recommend the 1.4. I even dropped mine, attached to the camera the other day and it survived!