GlobalFastDelivery via eBay offers this 4-Port USB Wall Charger with Four International Adapters
in Black or White for $9.99
with free shipping
. Outside of the below mentions, that's the lowest total price we could find by $3. It features adapters for the US, UK, EU, and Australia.
Close prices: MidnightBox
offers it for $6.95 plus $3.99 for shipping, and HDE via Amazon
offers it for $10.95 with free shipping for Prime members.