I have an older version of the Lenovo Preferred Pro keyboard. Mine's the black IBM model with square corners... I have a 2nd that has never been used, but I tossed the box and the wrist rest. It's very solid, still a membrane backed keyboard tho. Medium firm keys, and it's easily washed. The top tray/frame is what holds the keys, you can take the whole tray off with the keys on it and hose it or stick it in the dishwasher.
If you're interested I'd be willing to part with it... It's PS/2
I pondering getting the Enhanced model that has the multimedia keys.