I would definitely recommend the Flight travel series as well, especially if you don't mind the plastic back and sides. At that $50 / 50€ price range, I'd say they are easily the best value for money. If you want a concert scale uke but are ok with a soprano body, the long neck travel sopranos are extremely good. You can get one from Thomann, for example, with a fair price. They don't do setups but you don't really need one with the Flight anyway.
If you specifically want a concert body ukulele, I would try to stretch your budget to around 100€. I find that anything under that will just get you a bad concert uke. If you can afford that, I would look at the aforementioned Southern Ukulele Store and other UK dealers like World of Ukes and Uke Room, and brands like the ones mentioned before: Kala, Ohana, Baton Rouge, also Kai and the fully wooden Flight models. As I said earlier, if you buy from big music stores like Thomann you won't get a setup so you might get a uke not in very good shape. It's generally safer to buy from specialist uke shops. Unfortunately, I don't know any in France. There's a few in Germany that I know but they mostly sell more expensive ukes.