You might look into giving regular off-the-shelf 802G wi-fi equipment a try. You can buy a pair of wireless access points and a pair of 24 dBi parabolic antennas for under $300 - much cheaper than D-star! Set these up as a point to point network. I have heard of some LP FM radio stations which use this type of set-up over 2 to 4 mile hops as studio to transmitter links.
A number of years ago, I did some limited experimenting at home just for the heck of it. I used wireless WiFi for rig control. My Kenwood TS-2000X was connected to my desktop computer. I had my old laptop computer connected to the desktop computer via 802B WiFi. Using Microsoft's Netmeeting software, I launched and operated Kenwood's remote control software (resident on the desktop)from the laptop. Receiver audio was streamed live to the laptop as I tuned through the bands.
I did not try transmitting, as I did not have a mic for the laptop- but had no problem placing the rig into transmit mode using the remote control software.
I recently built a new audio interface and got a new laptop with built-in 802G. I am hoping to try experimenting with this setup again in the future, this time getting full RX/TX going.
Something you might want to give a try. If you are already running a network or WiFi at home, you could try all this out and see how it works for virtually no $$$$ investment.
73, de Tom, KA1MDA
www.ka1mda.org