I think you can get an 88-key controller with pads, knobs, and sliders for $300, but "less expensive" usually means "lesser quality," if not in the overall build then in the key action. As long as you're going to be the person using it, you'll definitely want to see if any nearby musical instrument stores have keyboards set up that you can try, to see what you think of the overall feel and especially the key action. You may or may not care about the type of keys (lever-like "diving board" organ-style keys versus box-shaped piano-style keys), or whether the key action is graded hammer scale versus semi-weighted or unweighted; only you can know what sorts of trade-offs you're willing to accept in striking a comfortable balance between price, quality, and features. And don't forget that if you're getting a controller, you'll still need to get some virtual instruments or VIs to play with it-- although there are many free VI plugins available to get started with.