The high-end of ergonomic mechanical keyboards are things like the Maltron or the Kinesis. Recently, there are projects which make use of 3D printing like the D

The high-end of ergonomic mechanical keyboards are things like the Maltron or the Kinesis. Recently, there are projects which make use of 3D printing like the Dactyl Manuform. Somewhat cheaper than these approaches is to go for a split keyboard, and 'tent' each of these halves. Ergodox is probably the most popular of keyboards like this; but there are smaller/cheaper keyboards like the Corne keyboard.