I got a couple of ECO tubes (and tailcap and glass lenses) from TKGEAR. They are not on the website, but just e-mail Brian. He's a super guy to deal with.
[email protected]
www.tkgear.tk
Only source I found for the booster head was Longbow. They did not have any ECO tubes in stock, but a few weeks ago they were talking about having some in 6 weeks. If you want to wait, you may get lucky and find both an ECO tube and booster head from the same source.
http://www.longbowonline.com/
Additional accessories that I found useful were:
- MiniMag filter kit -- fits the normal heads.
- Surefire F04 filter makes a good diffuser for the normal size heads
- Telescopic sight - flip up covers can be found to fit the booster head (about 40mm outside diameter).
- 1/4" camera lanyards can be found online or at most camera stores.
A lot of the places I contacted never had the accessories in stock -- just had them on the websites in anticipation of getting some.
The one thing I never got an answer on was an inexpensive belt clip, although there is a $25 Ti version available.