Alan, what you want to look for is a luer lock cap or stopcock. That is the the thread pattern for a syringe. Ask someone in the medical or vet field you know. I could mail you some if you don't have any luck. They're suprisingly hard to come by, but nowhere near as hard as getting an actual needle for a syringe which works great for sucking pesky air bubbles out of a laminate.
Great, thanks. I'll start asking around.
Alan