DLJ,
I did purchase two complete air stations(base and disks) from a Vertex dealer.(Ted at Forever Green) I also purchased their weighted airline.
It just so happened that the dealer had a used and rebuilt pump for sale at that time also which allowed me to get the 3 main components of a system all in one place. I plan on adding a third diffuser station next spring so I do know that they can be purchased independently of a complete system.
I still had to supply my own manifold, housing box, pressure gauge, and ball valves, etc. but I came in cheaper than if I had purchased the pre fabbed system by Vertex. Still had alot of time invested in it to get it working though. Budget wise for me I was able to get the pump, air stations, and weighted tubing from a normal Vertex system and then build it or DIY the thing within a price I could afford. I can tell you that my housing box isn't nearly as pretty as the Vertex box...
I am not sure exactly what pumps they offer in their complete systems. Mine was a Brookwood that I believe came in on a trade in thru that dealer when a customer upgraded their pump. I think they use Brookwood pumps in the prebuilt systems from Vertex but maybe Ted or Sue can chime in on this.
