Yeah it's expensive, but much cheaper than making a new one!
I see a lot of people get stuck at the wheel stage when restoring vintage bikes. A complete wheel - if it has a good rim (true and not rusted), sound spokes, brake with backing plate and shoes, operating arm, torque arm, axle, axle nuts, bearings - that is ready to drop in, can make a huge difference. It's a long way from a bare hub and a rusty rim to a usable wheel!
I'd prefer to pay 50 quid, but if this was exactly the wheel you were looking for, 200 might be today's "retail" price?
Cheers
Leon