I got the Citroen cross bars. they were a bit expensive (something like 100GBP i Think) but looks really good on the car. Easy to fit as well. I´m actually not taking them off after i´ve used them as i think they look awesome
It was pretty much hopeless to find a cheaper option in Sweden as the cactus roof bars are crazy wide and oddly shaped.
I Went for the Thule ranger 90 soft roof top box, and i am super pleased with the look and how flexible it is. It´s also a great option if storing space is limited as it folds neatly into a rather slim bag.
I got the citroen ones for €140 and a 320l roofbox for the same price from an online source. Pretty much any roofbox will do but you'd probably be best going for the citroen cross bars as they look really cool and fit really well. I've left mine on since attaching last week. Is there really that much of a mpg issue? They seem light enough!