They cost $2.70 each (£1.80), or for 5+ $2.39 (£1.59), or for 10+ (£2.12). When ordering more than 5 remember to enable bulk rates, this adds a delivery charge but the prices calculated above include this, and you still save more.
Green android product link
You can also get a pack of 4 (one of each colour) for $8.10 (£5.38) shown below:
4 Colour android pack product link
I have ordered lots of the Green android cell phone straps, and I will post an update with images when they arrive!