Depending on where you got them, they should be able to send them for repair (at a fee). For some reason they only allow you to do this within your warranty period but you can always try and contact Luxottica, who manufacture them, and see what they can do.
I purchased mine from a large department store in Australia (Myer) through Sunglass Hut - they do have a half price replacement policy if you damage your sunglasses. If you break or scratch them within the year you can buy a new pair at 50% discount.
Also another thing to consider - maybe your house and contents insurance may cover them?
Or try the optometrist - they may do it for a fraction of the cost.