Meritline offers its Mini Wireless Bluetooth v2.0 USB 2.0 Adapter for $2.99. Coupon code "MLCKP03BNL1" cuts it to 95 cents. With free shipping, that's the lowest total price we could find for a similar adapter by a buck, outside of the mention below. (It's also pennies more than our June mention of a similar item.) Coupon expires after 300 uses.
Expect this item to take two to three weeks to arrive.
A close price: Several sellers at eBay charge around $1 for similar adapters.
FreedomPop offers its refurbished Freedom Spot Photon 4G Hotspot in Platinum bundled with a FreedomPop 2GB Internet Access Trial and 1GB bonus at signup for $29.99 with free shipping. That's the best price we've seen for this model and $60 under the lowest total price we could find for a similar Hotspot alone elsewhere. (For further comparison, we saw a similar model bundled with 500MB of 4G Internet access per month for $49.99 with free shipping.) It provides WiFi for up to eight devices at once and has a battery life of up to six hours while unplugged.