Mechanical keyboards are just like any other product - you get what you pay for. A $60 mechanical keyboard would be a step up from a $20 membrane keyboard, but there's also the quality factor. I paid $60 for a Cooler Master Storm a few years back and it feels like a $60 keyboard. Whereas I paid $130 for a Corsair K70 and it feels like a $130 keyboard should.
While I agree with "you get what you pay for" in general, there are some exceptions. The CM Storm Quickfire I bought (~70) is higher quality than the Logitech and Razer Mechs I've demo'd. I think price/quality balance is the most important..some people think 150.00 on a Ducky KB is worth it...others disagree.