Raspberry Pi Zero has been quite popular when it launched due to its $5 price tag, excluding shipping and taxes. It’s been too popular actually, as manufacturing could not keep pace with demand, and resellers soon had to show it as Out of Stock, or simply decided to complete pull out the product page such as Element 14.
The supply tightness has lasted a few weeks, and recently I showed on GearBest for $19.10 including shipping, but it’s now out of stock, and the company expects to get more boards mid March… This also led to a website called whereismypizero.com which automatically tracks stock on some of the main distributors, namely Element14, Adafruit, The PiHut, Pimoroni, and Raspberry Pi Swag. The good news is that it is back on Pimoroni, where you can get a Raspberry Pi Zero board for 4.25 GBP ($6), unless you live outside of Europe, and you don’t need to pay VAT, and it’s back to the original 3.54 GBP (~$5) + shipping.
But I don’t suppose it will be in stock for very long.
[Update 24/02/2016: Out of stock in Pimoroni, but now in stock at The Pi Hut]
Thanks to Gabe for the tip.