I love mechanical keyboards. The one I have isn't 'ergonomic', but using it still helped a lot with hand strain. They usually cost more ($100+) and they're a little noisier than a typical keyboard, but they're very, very sturdy and feel great to type on.
I'm using the Matias Quiet Pro (
http://matias.ca/quietpro/pc/) right now for noise control, but if you find a mechanical keyboard with Red Cherry switches that will also be relatively quiet.