Hi Korky,
If transfering large sums, the Turkish banks charge more than the UK ones and it tends to be directly linked to the amount of money being sent. I bank with Garanti (in Turkey) and HSBC (in the UK). HSBC charged me about £21 to transfer £19,000 and Garanti charged an additional £47 to receive it.
So, the complete transfer cost £68
Then, when I transfered £1500, HSBC charged the standard £21 but now Garanti charged £11.
It appears the Garanti charge around 0.5% - 0.75% commission.
Glen.