It's cheaper to cover concrete block with studs and drywall than to pay people to plaster it (In the states anyways).
Used to - houses had 3/4" ship lap siding interior with only a 1/4" gyp bd on top. I helped a buddy tear all his old gyp out and we stuck with exposed ship lap. That ship lap actually looks pretty cool in the right context, but it won't be cheaper than gyp now. Nothing will be. You're only option with cheaper would be to somehow find a place with some salvageable lumber that you can get for free and put up yourself.