I looked into this previoulsy for my B7 and dismissed it due to the costs and effort involved. You would need to change both hinges, both gas struts and add the spring and cover to each hinge.
I estimated around £200 to do the job, as the new hinges will also need painting to match your car's colour. This of course doesnt include labour to fit the parts - not that difficult to do though.
I just couldnt be *****!
