REI Garage offers the Avenir Presta Valve Bicycle Tube for $1.73. Choose in-store pickup to avoid the $5.99 shipping fee. That's tied with our mention from two weeks ago and the lowest price we could find by $7. It fits 26" wheels.
Of note, a similar tube with a Schrader Valve is also available for $1.73 with the above shipping options. That's tied with our mention from two weeks ago and another price low, this time by $4. However, it fits 20" wheels.