I prepare meat and especially fish in sunflower-oil.
Does anyone know how this compares nutrition-wise with olive-oil etc.?
It only costs a forth of the price of olive-oil and I’m a poor student…
I personally dont use sunflower or canola oil. I get polyunsaturated oil from fish and omega 3 tablets and monounsaturated oil from mixed nuts and olive oil.
Furthermore, I would never cook food in a polyunsaturated oil and would cook food in olive oil only if I had to…I have coconut oil for that, and a george forman grill so I dont have to use oil.
I would save the extra and use olive oil on your salad and give the sunflower oil to someone you dont like 
Extra Virgin Olive Oil will be superior as it will not have been raped of its goodness by being treated at high temperatures.