don't bother with a PHX. There are better bongs available.
RooR percs are being phased out, so you'll be exceptionally lucky to grab one- they're literally the Maserati of bongs- you CANNOT do better. Period.
LUX Scientific, a new offshoot of RooR US, is now making mini-percs with the same design as the RooR percs, for a fraction of the cost. If you're interested, I can absolutely help you obtain one (I've got one coming in the mail as we speak).
Toro bongs make the best dome percs (the PHX style)- almost no drag whatsoever, nearly as good as a RooR, and just as well-constructed.
ZOB tubes are pretty cheap g-on-g bongs, and many have dome percs, again, which are pretty well constructed.
The quality control at PHX is a bit lacking, which is why I don't advocate buying one. The joints always seem wobbly, and there's way too many bubbles in the glass. That, and the drag is horriffic.
If you can't find a RooR perc, drop me a line. I know people who can definitely help.