Hilmi Leather is the shop i always visit, you can find it near the harbour. This year Hilmi talked about moving the shop to Ataturk, so maybe you will find him there.
I have bought a lot of leather jackets (for myself and friends) at Hilmi Leather and both the price and quality has been superb.
Pay him a visit, you wont be disappointed.

You can view a larger picture by clicking on the pictures below.