The weekend before last I went to stay with the lovely YorkshireLass and we went for a little trip to a Haberdashers called Bond's on the outskirts of Leeds. Haby is the British word for Notions, and is all the zips, buttons, cord, thread etc bits and pieces. We spent 3 hours in the shop and spent quite a bit of money.
My local haby place sells only black or navy invisible zippers and they are £1.20 each, so I didn't feel like I was too silly buying all of these. They now have a special box to live in and I've added all the invisible zips from my generic sipper box to them, so when I want an invisible zip they will be very easy to find.