Amazon offers Prime members the New Balance Women's Go 2 Tights in Black for $20.27 with free shipping. (Non-members can spend $35 or more to qualify for free shipping; otherwise, it adds $5.58.) That's the lowest total price we could find by $13. They're available in sizes M and L. (Size S is available for a buck more.)

Of note, they're also available in Watermelon in size M for a buck more.