Hydraulic Dampers

I was wondering if someone might have a North American supplier for dual action hydraulic dampers? I've been searching and can't seem to find anyone who can supply these at a reasonable cost? Single action (extension or compression) dampers are fairly common and relatively inexpensive but dual action one's seem pretty elusive? Thanks for the help.

I did find a manufacturer and distibutor here in BC but a single dual action damper with a 4" stroke was $115.00. I'm starting to think that these dual action dampers are only a specialty item and hence the high price? I did see somewhere on the net that someone built there own dampers with a metal tube, some threaded rod, a few metal and rubber washers and some bolt? If anyone has any experience with this I'd love to here about it, otherwise I'll give it a go and let you know how it works....;)