Well I believe I've found a single-supply instrumentation amplifier that could be used: http://www.digikey.com/product-detail/en/INA332AIDGKT/296-12204-1-ND/413491
If I've understood it correctly, I would connect both the + and - outputs of the sensor to the chip, then add a resistor to adjust the gain to be about 82x. I should get a smooth voltage output from it, which I can read with the Arduino core. And the whole thing would only cost about $2.00 extra.
Just to add some closure to the topic, for future people who might stumble on this thread, I hooked up the sensor to an instrumentation amplifier and had awesome results!
I used the INA122 instrumentation amp (planning to use the AD8223 SMT chip in the actual PCB), hooked up the sensor's + and - outputs to it and added a gain resistor. I was able to read the entire range of sipping and puffing through a 10ft long tube connected to the sensor. Here is a complete write-up of what I did: http://jason-webb.info/2013/03/working-breadboard-prototype-of-an-open-source-sip-and-puff-interface/