Just as clarification, I bought mine for $20 through Wabfab, who just had them drop shipped from Trail Gear. Trail Gear sells them for $19 directly, so obviously he's probably letting Wabfab have them for something significantly cheaper than $20.
ARB sells a version for ~$11, that is the better way to go IMHO. Any Air Locker dealer should have those I'd guess. I keep forgetting to ask Ben when I talk to him.
But I occasionally flip through the pneumatic catalogs and see what I can find. ARB's 5mm is not a common size, although someone makes it. If a 3/16" fitting will work, those are dirt cheap (like $3).
'91 Pickup - Imelda / '08 Tacoma TRD - Donna
'09 Kawasaki KLR650
'98 Rhygin Juke SS / '12 Gunnar Rockhound 29 / '16 REEB Dikyelous
"Our task must be to free ourselves from this prison by widening our circle of compassion to embrace all living creatures and the whole of nature in its beauty. Nobody is able to achieve this completely, but the striving for such achievement is in itself a part of the liberation and a foundation for inner security. " --Albert Einstein