It is a little more complicated than that and MIDI controller keyboards can come in many varieties, differing in price and in features between different models. Piano keyboards will generally try and imitate a piano playing experience with sampled piano sounds and familiar hardware like foot pedals. A MIDI keyboard controller on the other hand either includes a hardware synthesizer on board in which case it is probably best called a synthesizer, or it acts as an interface to a computer running virtual synthesizer programs.

The models that do not include their own synthesis engine are much cheaper but can still be complex pieces of equipment due to the controller functions that they include. Yamaha MIDI keyboards and Roland MIDI keyboards are two popular brands but other companies have developed innovative models in recent years. The remote midi keyboard by novation has become a standard in many music circles, and they have many varieties of this model available. Korg MIDI keyboards and casio MIDI keyboards are also popular with different features and models available.

One function that affects the price is whether the model has a weighted action in the keyboard, many cheap MIDI keyboards do not and have a plastic kind of feel when they are played. More expensive MIDI keyboards will have either a full or a semi weighted action and will feel much more responsive to touch. Aftertouch is another feature sometimes left out on cheap MIDI keyboards, yet most professional keyboard players find this to be a necessary function. The third effect on price is simply the number and quality of the knobs and sliders that control the MIDI data along with the piano style keys.

Most keyboards today are USB MIDI keyboards and connect through the USB port to a host computer. Some however do require a MIDI interface that will need to be installed on the computer before they will work. MIDI keyboard controllers connect through the MIDI data protocol and effect and alter how the synthesizer engine creates sound, whether that engine lies in the MIDI keyboard itself or on a host computer running virtual instruments. There are many different models and brands available, it is best to do your homework before you buy, and probably better to not get the cheaper models as you can grow out of them rather quickly.