A midi controller is just a small keyboard with no sounds in it. All you use it for is to hook it up to your pc or to a sound mod and play its sounds. I know alot of people have the DJX keyboard which is cheap too. I dont know much about keyboard with sounds in it cause i just use a midi controller.
It depends on what exactly you want the keyboard for. As a MIDI controller, or as a sound source? If your setup is mainly computer-based, then you should go with just a MIDI controller. But then again, a regular keyboard will do the same thing.
A thing you should look for, when buying a Master Keyboard( Keyboard without sounds in database) is that the keys are wide enough for you. They sell these tiny lil´ keyboards for nearly no money, but when you try to play something you pressing 2 or 3 key at one time so it´s fucked up. But you will get ok equipment for ca. 50 bucks (Euro and Dollar is quite the same price i guess).