Getting into a little more industrial type fittings. I believe Chemline (
www.chemline.com) makes valves like that, so if you can find a Chemline supplier you might be able to try that. But it won't be at your typical plumbing supply counter, you're going to have to go into more like suppliers to the chemical, oil&gas sectors, etc. When I looked for a Chemline valve once it was actually up in your area where they were (Edmonton, not Calgary, I mean). I'll have to see if I can find the invoice then I can PM you the contact information. The only problem is that these places usually want to set up an account so you can buy from them and that's hardly worthwhile for a single $10 valve.
Incidentally I did once buy a plastic needle valve with 3/8" NPT fittings from Jayson once at SWC, so you could try him. Otherwise, I'm sure the guys at Ocean Aquatics might be able to set you up with something, I'd drop them a line and ask about it. They can usually get things like that.
And ... failing all that ... then ... ya' what Brad said.
