Personally, the first place I always check is Amazon purely because of the free shipping and often cheaper price. You do have to be careful because some listings are counterfeit but Amazon is very good with returns and will always choose the customer over the seller. I just checked the Yonex Nanoray 10F listing here and it's legitimate: https://www.amazon.com/Yonex-Badminton-Pre-strung-Half-length-NR10F-RED/dp/B06WWLXG17/ref=cm_cr_arp_d_product_top?ie=UTF8

You can also check out badminton warehouse but I haven't personally used them to purchase a racket so I can't attest to them.