Although i found these could be useful safety tools i looked around and didnt feel like spending $500 on an airbag.
I ordered on of these last week for approx $150 CAD (shipping and taxes included).
http://www.airbagjacket.com.sg/product_details.php?category_id=61&item_id=5
I received it yesterday but due to weather havent had a chance to test it out (maybe in 1h i will go for a ride). I got a 2XL size and the vest fits comfortably over my existing jacket, i dont really even notice it other than around the collar area, its not too heavy and made of a thick textile mesh.
The buttons and zipper seem to be thick and decent quality, the CO2 cartridge is a weird size (38g) i didnt feel like buying extra's from the company at around $30 each but think i can find them online or at a hardware/marina.
if i get some spare CO2 i will play around with it more and test out the performance.
-Dingo