George, i would get one from the Uk. I bought a Galaxy Ace when i was in the Uk last Christmas, the cost was £80 including sim card, the same phone over here was 600Tl. If your not going over for a while ask somebody to bring you one.
I used to get texts from Turkcell offering a very good deal on contract for 29Tl, when i enquired about it in the Turkcell shop i was told i couldn't have a contract as i was a foreigner, it may have changed but i have never bothered since especially as there are so many cheap packages offered by Turkcell.
I also have an international text package which gives me 100 texts for 15Tl, 1 page is one text, you can also get 30 texts for 7.5Tl