This one is a bit odd...I've looked pretty much everywhere and have only found it reasonably priced at the home brew suppliers.
Haven't found anything like it in the Mass Market stores, the wholesale places I get some of the parts I've been re-supplying are actually a fair bit more expensive than the Brew shops, and it can be had in the US for about $2/ft. So if you're already getting stuff in the US and shipping to a US address you can save, but for the amount you need (<10 ft) Hopdawgs really is the best deal we've found so far in Canada.
If I can figure out who's supplying it wholesale to the guys in the US, I'll get 100 feet and should be able to knock it down to $2-$2.50 a foot I expect, but like I said the wholesaler I've used for most of the parts are a multiple of the usual retail price. There are a few things like that, like the camlock fittings that work so well with the tubing, what Austin Home Brew sells for $5, are $25 at McMaster Carr...Go figure.
JQ