PSM, even with the NMS extension isn't going to give you a price elasticity curve. PSM by itself is an attitudinal model about pricing, and with the PSM addition, we make it a little volumetric. With the extension you can model the elasticity of demand to price, but it creates some odd findings (e.g. at very low prices, demand increases as price goes up). For this and for the fact that I'm not aware of a lot of empirical support for PSM, I don't view it as a viable alternative to CBC when CBC is possible.
For the calibrations of purchase intention ratings to purchase probabilities there is an extensive literature, some of which is summarized in the great Design and Marketing of New Products book by Urban and Hauser.
Personally I like to use PSM, with our without the extension, only for new-to-the-world products. When a product inhabits a market with competitive products, I think CBC is hands-down the better way to go.