Cheapest Place for Oxygen Regulator and Diffusion Stone?

I am thinking about purchasing an oxygen regulator and diffusion stone.

Any suggestions on the cheapest place with inexpensive shipping?

Williams' kit is $49, I'm sure something comparable can be found cheaper.

I am very interested in this, too. Someone help!

i bought a regulator for those little red O2 tanks they sell at home depot and a wand that has the stone affixed to the end of it. i had 3 problems:the regulator was pretty tricky to operate, it spun for a while before suddenly going full blast and when i tried to unscrew the regulator it got stuck and lots of gas escaped. once the canister is empty i had to find a proper way to dispose of it, you can't just throw it in the trash. lots of people use this setup with no problems but it was too rinky dink for my liking.

i decided to buy a 20 cubic foot O2 tank and regulator at harbor freight and it's made the whole oxygenation process very smooth. cheap is relative but i paid about $84 for the tank and $40 for the regulator which was cheap in my book. i can't tell the amount of gas going into the wort but i can regulate the flow pretty well with the regulator from a stream of small bubbles to a roiling volcano,i did that by accident, turned the regulator the wrong way once i don't have to worry about how much gas is left in the canister or what to do when it's empty. the 20 cubic ft should last for many, many batches.

the harbor freight oxygen (and acetylene..) regulators work very well and are probably the most inexpensive new regulators you're going to find. i've been using a set for several years now and haven't had a single problem with them. even the gauges are decent, something that is usually lacking in chinese equipment..