Regarding sales contracts - 2 more interesting points if things go belly up:
1. If your sales contract has NOT been notarised, a solicitor can only make a claim against the seller for the return of your cash via the courts. An un-notarised contract does not give you the right to seek your Tapu in place of cash. So if you win your case (and there are no debts already against the property), the courts can order a charge put on the property, so it cannot be sold to anyone else. But if your seller has no money and you want your money back, all that can be done is for the court to order the property to be sold at auction. Sadly of course, you willl be unlikely to get all your money back, plus you will owe the solicitor their cut.
2. If your sales contract was notarised, the solicitor can then apply in court for either your cash (as above) or for the Tapu.
So under no circumstances should you rely on your contract to provide you with a property. In my opinion, the only way to buy with confidence in Turkey (for a foreigner) is to pay a small deposit and not pay any more until your Tapu is available.
Thank goodness there are a large amount of reputable builders about, or none of us would own our property here!