Best4Choose via eBay offers two Neon LED Car / Bike Tire Valve Stems in Blue for $1.21 with free shipping. That's tied with our June mention and the lowest total price we could find now by $2, outside of the mention below. It's compatible with US and UK valves. Note that it ships from mainland China and may take three to five weeks to arrive.

A close price: Warm Winter via Amazon offers a similar item for $1.75 with free shipping.