There seems to be loads of cheap glasses websites in the UK that I imagine would post to Europe. I use spex4less.co.uk However in the past I used a similar website and got 3 pairs for about €40, but they didn't have the correct prescription in them, they were generic prescriptions but each of my eyes needs a different strength. Also these websites offer cheap frames, but the dimensions of them are often not very good, ie, their Wayfarers which I wear are nowhere near as good as the RayBan frames I wear, so I ended up buying RayBan frames, albeit at a large discount of around 50% online compared to the high street. If you already have your prescription finding cheap glasses online should be a no-brainer though.