You can never have enough good quality basic shirts (okay you can, but I don’t even come close ;). Last sale period I kept my eyes open for Acne and Alexander Wang shirts and I was happy to add a grey/blue one from T by Alexander Wang and a dark blue one from Acne (men’s department: tip!). But they don’t always have to be expensive (although the Acne one was only €25,- bargain right?), H&M and COS also offer great basics. The Isabel Marant collection for H&M had the perfect linen tees and I bought a white one from the men’s department. But I’m most happy with the perfect white tee from the H&M autumn collection. I wear it so often but the fit and fabric are still perfect.
A little tip when buying: feel the fabric and whenever the fabric feels really great check the label to be sure its 100% (or close to 100%) cotton/linen. And unfortunately from own experience: wash the shirts in a mesh laundry bag to avoid small holes. That way you can enjoy your shirts the coming seasons as well!