Yonex BG-65 is probably the best selling badminton string in the world. Modestly priced all purpose string. String is 0.70mm. Available in white only.

$20

Yonex BG-85 is an ultra thin high performance synthetic badminton string that incorporates Vectran fibers for high repulsion power. More powerful smashes and better tension maintenance. 0.67mm. In white.

$25