Here's a cute stamp that I got while in Istanbul, Turkiye this summer. I also got this black adhesive tape as well. I thought this stamp set was too cute with the little girl on it. Hope you like her. All the locations that I found selling stamps were in the Kadikoy neighborhood. I saw maybe 4 different stores that had clear stamp sets.
Would have been fun to keep searching, but the streets are long and the shops can be far apart. If I spoke any Turkish it would have been helpful, but the store owners were more than nice and even helpful in telling me where else I could go to find similar products.