I have eye on Aegean Airlines because every year I need to take 4 one-way flights with them to retain my Aegean Gold status (Star Alliance) and earn 12000 Aegean Tier miles. Basically I travel to Warsaw 4 times per Year with them and one trip give me 3734 Tier miles.
I notice that currently they have promotion code 20Aegean which can be used on return flight booked at their page.
I found out what You can travel to IST for 107.54 GBP using this code, and You can earn 3042 Tier miles.
I will write post about easiest way to get Star Alliance Gold status with Aegean. I’m Gold with them since 2014. Sadly I cannot use this promo for flights to Warsaw, because you cannot book this route (I use kayak or momondo to book it).