If you're looking for a keyboard, I recommend Yamaha keyboards. The Yamaha P-125 series is a nice keyboard.
Look for Graded Hammer action or something like this in the description: "WEIGHTED ACTION: GHS 88-key weighted action, heavier in the low keys and lighter in the high keys"
Make sure you get a sustain pedal, stand and bench to use with your keyboard.
I'm on a budget
No problem, you can start with a more basic keyboard. I will still recommend getting a keyboard stand and bench to make sure you are playing at the correct height.
This is a good option to start and as of this writing is less than $120.
Do I need a keyboard or can I use an acoustic piano?
I'd recommend an acoustic piano whenever possible. Just keep it in tune. You should tune your piano at least once per year or at the change from summer/winter and winter/summer.
The keyboard I use in the lessons is a Yamaha DGX-625 (discontinued) but you can find newer DGX models online.
For some of the funk/organ lessons I use my Nord Electro. Again, this model is discontinued but you can find newer models.
I also use a Hammond SK-2 for the organ lessons.
I recommend a nice adjustable bench which makes practice more enjoyable.
If you need a MIDI interface, iConnectivity is a well-rated one.
Finally, a good metronome is helpful.