Steve,
Cello's a bit backlogged with Katrina-related issues, so I'll answer for him if I may.
New ZYX prices are always shown in Mehran's (Sorasound's) A'gon ads. The current ad is here:
http://cls.audiogon.com/cgi-bin/cls.pl?anlgcart&1129729261He also has demo/review cartridges available from time to time. Give him a call or email if that's of interest. As posted by many here, Mehran is one of the nicest and most honorable men you will ever meet.
Compliance for all ZYXs is 12cu in the vertical mode, 15cu lateral. I normally recommend that people order their ZYX with the optional silver weight. An ET2 might not need it however. Do you know your arm's eff. mass in the lateral plane? If it's high (> 16g) like many other air bearing arms, you might not need the optional weight. The Airys weigh about 5g without the weight, 8-9g with it.
I'd be interested in hearing about how one of the top ZYX's performs on an ET2. The Airy 2, Airy 3 and UNIverse all easily outplayed a 901 on the three pivoting arms I've compared them on, so in general I concur with Cello's recommendation.
P.S. There's one more option on these cartridges: copper coils or silver (same price). Cello and I have A/B'd copper and silver coiled UNIverses in both our systems. On ZYX's top model, the copper coils are more neutral, the silver coils are rather warmish or smoothed. We both prefer the copper but fans of the traditional Koetsu sound would probably choose the silver.