Advice for a foreigner | bir yabancıya tavsiye

Dear friends, sorry to ask in English, but I couldn't find any other online car forum in Turkey.

I came to work in Istanbul recently and I am looking for any used car below 150 000 lira.

I think about VW 1303, Peugeot 405 and Citroen BX.

How do you think, are there any good service stations in Istanbul who repair old carburated cars?

Is it a good idea to go to the chain-services like "otopratik" or "bosch-service" ?

Do you have a service where a man comes and helps to find out a used car and negotiate a better price for you?