You are much better off going to a specialist and not through a dealer, I'd be very surprised if they go much lower in terms of contribution and that price is astromical. I had mine repaired by an ex Renault mechanic with a new clutch fitted and full service for £650 + Clutch price as I bought this myself. Needed 2 Synchros and another part which I can't remember the name of, have they only quoted you for a replacement box and not for a box repair? The whole box doesn't need replacing unless it's damaged that seems seriously overkill, mine was in at 8am and rebuilt and serviced by 6pm ready for me to pick up.