I've noticed pricing on AIS Class B has come way down. West Marine has a full Class B transponder for $500 now. Considering most receive only units are in the $200-$300 range minimum, thats really not much a premium for full features.
Also, I'm watching this trend of AIS being integrated into the VHF radio. Right now, Standard Horizon has a receive AIS only integrated into their latest VHF for about $350. I cant wait for that to be send/receive both because it would eliminate the need for either a second VHF antenna as well as the radio has a VHF on masthead already.