Dalyan is an up and coming area and yes lıkely to be a good investment and rental prospects in that area will gro PROVİDİNG you are prepared to spend some time marketing as rentals dont market themselves.

You imply in your post that you are buying an older property, which needs renovation and pool put in. Are you doing that or the seller? and also carefully check the build permission thoroughly, İ say this because certain areas are nature reserve in that locale.

Also if you post the price range you are likely to get some response as to wether the price is in the right range.