They must be about the luckiest people in Kalkan. I haven't seen any apartments or even villas double in price (except in theory) in recent years. Very few villas are rented all year and even if they were, there is no mention of electricity costs. With renters switching on air con 24/7 in summer and winter the bills would be horrific. Plus all year renting would double the maintenance bills. Add in all other costs eg. to service the original purchase price, tax,etc and you might make a small return which would pay for your hols. It looks more like a sales pitch.