all arko soaps and creams are highly recommendable.
Regards
oskar
Page created in Wiki for wetshaving supplies in Turkey. If you have any information, please add it: http://wiki.badgerandblade.com/index.php/Turkey_Shaving_supplies
Luc was linking to Turkey Shaving supplies which has a section on Istanbul: http://wiki.badgerandblade.com/Turkey_Shaving_supplies#Istanbul
That lists includes a T-Shop in Çemberlitas, which is where I bought some when I was there a few years ago. It should be handy for anyone visiting the main tourist sites. The price was the best I found: exactly 1 Turkish lira.