I disagree with the previous assessment, it does fit oversize (its how its supposed to fit). If you want it to look like a normal "slim fit" shirt than I would recommend going down a size. As a reference I'm almost always a 39 but went down to 38 in this shirt when I tried it on.
A lot of the permanent colors don't go on sale. You can usually find them on ssense and other online retailers that are more flexible with stock however.
Also I don't think Lanvin sneakers are over-priced when compared to the rest of the luxury sneaker market. They're priced slightly higher than GATs but significantly lower than other designer brands (usually 475 USD).