I will not buy one, unless they are for sale in say Italy when I travel there. But a helmet that can be obtained for close to nothing, folds up and fits in a purse or bag and that can be worn for week then recycled with no guilt about either money spent or landfill pollution; sounds like a winner for both the tourist and the host city, especially the smaller businesses that cannot afford parking.
This helmet doesn't look much worse than a lot of the helmets I see out there which are presumably CPSC approved.
And in response to I-Like-To-Bike, $5 for a one time use is a lot, unless you have to pay $35 to get that "real" helmet to rent that bike.
Ben