Since the aforementioned are two of the best highlights of Istanbul, a multitude of companies offer organised trips to both which can cost anything between 200 to around 400 Turkish Liras (TYR) depending on the company you choose.
I am of the opinion that organised trips are not value for money; they are typical tourist traps and best avoided by savvy travellers. In case you didn’t know, both can be done cheaply on a do-it-yourself basis without missing out on much.
1. The Bosphorous Cruise:
Take a day cruise offered by one of the commuter ferry services like Turyol. They have dedicated day cruises on the Bosphorous that last an hour and a half. The ticket is only TRY 15. The last cruise is around sundown, which is the best time to hop on a ferry to appreciate the beauty of the Bosphorous and take memorable pictures in ideal light conditions. There are no belly dancing and dinner combos on offer but I take those as a big plus. Take in the views of the strait without distractions.
You can take the ferry from any point served by Turyol. I took it from the station below the Galata Bridge (forgot station name) and disembarked at the Asian side by choice. The ferry does a round trip so you can return at the point where you boarded it.
2. Princess Island Ferry:
Büyükada is also served by many stations across the city. Take a one way ride and return at will. During summer time, it might be busy but ferries to Istanbul are dispatched around the clock: if you miss one, there’s always another one to take you back.
I took one from Beşiktaş and spent half a day at the island, roamed around at will, took a phaeton ride to the reserve, and bought another one-way ticket back to Istanbul, which made stops at both Kadıköy and then at Eminönü. The one way ticket cost TRY 7/8.
At the end of it all, I had covered the cruise jing bang in 30 TYR instead of a mammoth 400 TYR!