Although I've never been to Boston, have you looked at the Walmarts/Kmarts or supermarkets? I'm in Jersey and I've seen them in our local drugstores (CVS/Duane Reade) and the supermarkets (A&P, Shoprite, Pathmark, Stop & Shop). Although I've never seen them in Target though. They are either by the brita pitchers or by the camping goods/fishing/travel section.
I've also seen them offered on Ebay in case you're intersted.
And there is no strap. It's just a bottle, but if you do a search for brita bottles (I put up a question a couple of months ago about them), there have been some creative ways on how to keep hold of the bottle.
Personaly i think they are a little bulky, especially with the squeeze factor but I'll probably buy one in the end to save money. Good luck on your search.