Except at the "toy" end of the market, almost any synthesiser or electric piano you can buy today will have MIDI in and out.
Reading between the lines, I suppose the challenge you have is that you want a good keyboard, with budget sounds. That may be difficult to find.
I would recommend shopping around and basing your shortlist on the mechanical aspects of the instrument -- if you want it to feel like a piano, look at digital pianos; if you want it to feel like an organ, look at more "synthy" keyboards.
Then ensure that MIDI in and out is supported. Just for futureproofing, you should check:
- that you can use the keyboard to control other sound modules.
- that you can control the sound module from another MIDI source (like a sequencer)
It's an unusual keyboard that doesn't meet these requirements -- but you should check just in case.
... and finally, when you are trying out the instruments in the shop, use the sounds it makes as a deciding criterion.