Keith, this is an old topic and I don’t know if you’ve since arrived at a solution, but if you don't mind a tiny bit of soldering on your console, I expect you could use a standard Davis VP2 with just a Yagi added to the receiver and the stock omni antenna on the anemometer transmitter.
I'm able to receive my neighbor's Vantage Vue through light trees and a wall from ~600’ with standard antennas, so something like this cheap Yagi (claims 14dBi) should make a huge difference in range.
http://www.l-com.com/item.aspx?id=25507And if you REALLY want maximum receive sensitivity you could add a low-noise preamp like this mounted at the antenna.
http://www.advancedreceiver.com/page4.htmlYou could probably get away with really good quality RG-6 coax for a short run to the antenna, but something like LMR600 would be lots better (and more expensive) for a long run. That's a big advantage to using a preamp, as with 19db of gain at the antenna you can afford to use a very lossy, cheap feedline. Looks like you're in a fairly rural area, so with luck there are no excessively strong interfering 915MHz signals to overload a preamp.
If using a preamp be sure the console’s “Retransmit” function is turned off, though!
Of course, you could also add a higher gain antenna to the transmitter, but this would invalidate the FCC (or Industry Canada) certification if that's a concern.
Even a lovely GaAsFET preamp, good coax, and a Yagi should be appreciably cheaper than the Davis approved solution.