Quality or not, designer or brand, I don't think it's very smart or necessary to buy a t-shirt (even if it may be nicely cut and have puffed sleeves) for over 50€.
Having this said, I still bought a very cute black short Diesel t-shirt with puffed sleeves a couple of months ago for 50 euros (or actually I paid "only" 30 € for it since I bought it from the shop where I occasionaly do a shift or two and thus still have my personnel discount). Quite costy, but it was perfect for most of my high-waist skirts or over some sleevess dresess.
But it dissapeared in Amsterdam. Almost right in front of my eyes. When I was there over the new year's we were 11 people staying in the same flat so it was a bit messy. I had my shirt and a dress hanging over a chair and one moment they were both there and the next only the dress. I thought it had fallen on the floor and got mixed up with someone else's stuff but everyone checked their bags there and at home again but the shirt had just vanished. And it hasn't been found in the flat by this day. I'm afraid it somehow just, eh, got thrown away in the trash when we cleaned after the NYE party.
It's sad beacuse I really liked the shirt. I'm almost considering to buy a new one, if there are eny left, they only had a few. But that's really stupid, right? To put that much money on a t-shirt. It was more of a blouse actually, so is it ok then?