Isn't the Longacre Hot Lap system pretty much the defacto standard for HPDE timing? They're about $250 for a transmitter/receiver pair, but I think the club might be able to share one transmitter for track days and we can just buy our own receivers for $190 each.
http://www.racerpartswholesale.com/hotlap.htm
I'm not sure there isn't something better out there... this stuff has been around for a while... but at the same time, these are so popular, if you go to an event w/o the transmitter, there's still a good chance someone else would have one setup track side already!