Very cheap check valves?

I've been reading a lot of the posts on building your own manifold for distributing CO2 and a lot of the discussions end saying they can't find cheap check valves. On eBay there are ghost generator check valves for next to nothing, $1.25 each that have 1/4 barbs on either end if I ran this inline after the manifold wouldn't work? Anyone have any special knowledge on these types of check valves from experience? They are rated up to 150psi, but say they have a cracking 0pressure of .5psi, any clue what this means, I assume it means anything under .5 can't flow in either direction, any help would be much appreciated, if they work then I could easily make a 3 way manifold for $12