Genuine camshaft was £450 two years ago, then add all the followers, seals, bearings etc another £250 if you haven't had a cam belt done recently another £150 and finally about 6 hours labour.
Cheap kit is £300 for cam, followers and bearings but seems hit and miss on how long it lasts.
You can get a cheaper camshaft (which apparently comes from the same factory as the vw one) for around £250-300 I bought this one.