No waste pipe for washing machine - rough cost to install?

I'm looking to buy my first home. In the kitchen is a built in dishwasher under the sink, but the vendor has plastered over the wastepipe for the washing machine - he says the wall will need to be knocked through to plumb in the machine. He originally had the washing machine freestanding in the corner of the room. He's not happy to negotiate on price for the house, and I'm assuming this job will cost quite a bit, so trying to work out if this property is worth the money. My questions: - Roughly, how much would it cost to knock through the wall to plumb in the freestanding machine in the original corner? - What would the cost be to put a cabinet in front of the machine, with a breakfast bar above it? Any help would be greatly appreciated!