I went ahead with them in the end and bought what looked like a decent set of new lenses off ebay. The lenses are starting to fade, and removing them cleanly looks to be quite tricky. A layer of PPF or clear vinyl should do the trick to help protect the new ones.

That did cross my mind. There's an exact set that would fit on donedeal at the moment that look to have been resealed. They're up for €450 though... I'll fit the xenons first and wait to see if they pass. If not, that's probably the route I'll go down.