Of course other brands are even more expensive here.
But compared to the US they are overpriced IMO. (I had a look at the Nordstrom site which automatically shows me the US prices converted in Euros, and a l/s is just 12-13 Euro there!) And the price keeps getting higher. So I might as well spend a couple of Euros more on higher end l/s, where I feel the formulas are nicer and they are actually worth that high price.
Also I feel the quality in MAC l/s can differ a lot. One can have a smooth and even application and feel nice and hydrating, another one can look patchy and feel drying. And since I order all my MAC online I don't want to take that risk of ending up with a lippie I hate (well there's always a risk, but I want to keep it as minimal as possible). So if I see swatches that make me doubt if a l/s has a nice formula, I rather invest in a high end brand one where the quality is more consistent. I hope that makes sense