I believe they were 5mm diameter half round styrene rods, there are a few brands out there including Plastruct and Evergreen.
You will need to round off the ends once you've cut them to required length.
You didn't say where in the world you're from, so I can't advise you on a specific retail outlet but I'm sure e-bay would be a safe bet.
Good luck with your build.
I love Enterprise too and they had some fantastic props.