Redbear's Mini: $39.95 (Note: This is a uC and BLE combo).
Redbear's Uno Shield: $29.95
BLEDuino: $19.95 (if part of Kickstarter)
Bluegiga Shield: $69.95
After seeing these, I thought I'd try to make one; this is my bumbling process for making an Arduino Bluetooth 4.0 device at home:
Step 1: How to Create an Arduino Compatible Bluetooth 4.0 Module
I started working with these little Bluetooth modules in attempt to add Bluetooth 4.0 to my robot projects.