JeeNode is €18.50 and, you must assemble it, which to me doesn't seem like a great deal, but I understand your point. You are not the first person to ask for a cheap, small module. All I can say is that I and some others are working hard on DASH7 HW, and if you monitor #DASH7 on twitter during Jan/Feb, (or follow @jpnorair), there will be some product announcements.
There is talk of integrating an Energia environment (arduino clone for MSP430) into OpenTag directly, but right now I'm too busy working on HayTag. OpenTag and DASH7 are a lot more sophisticated than JeeNode is (or Arduino), so it's not so simple as writing an Arduino library for DASH7. I'm not even sure that's possible. But, it is possible to run an Arduino Environment (or Energia Environment, or Maple Enviroment) as a thread on OpenTag. That way, you can treat the DASH7 system just like a pipe, and not worry about the deep complexities of it.
If you know Processing and want to help with this, let me know. WizzMote and CC430 can support Energia, and HayTag can probably support Maple. HayTag also includes solar + battery, and it will be available as a bare module in addition to the normal, finished tag. The pin-out is somewhat limited given the tiny size of the device, but it has I2C, UART, and a couple of IO/AIN pins.