Aquamedic Calcium Reactor plus Dosing Pump is still on sale for $150.
does not come with calcium media, needle valve, CO2 tank... it's just the Reactor, the pump and the powerplugs responsible to run them. and other goodies I can dig out from the house. if I'm not mistaken, it's the Kalkreactor 1000 series. I've got no idea if it can fit a pH probe or anything, but I'm pretty sure that it doesn't come with one.
http://www.aqua-medic.de/seawater/en/11/kalkreaktor1000/
I'm basing this based on my pictorial comparison of having the reactor in my room and looking at it from the computer monitor.
again like I said, the media is still inside. I have no ability to clean it due to my current commitments to studies and work, so you will have to clean it yourself. please factor that in if it is a factor to your purchase.
Anthony.... if you're still keen, do get back to me ASAP to let me know. if not, I'll let it go to other people. (=