I use an LM-2 to log A/F, Pan Vac, nitrous fuel pressure, and nitrous bottle pressure. Certainly not as easy and clean as a Racepak, but it gets the job done for about $800.00 total investment including the sensors. I use a company called Transducers Direct for the sensors. They're ~$100.00 each. Pick the range you want to measure and the 0-5VDC output. Wire them into the Analog channels to the LM using shielded cable and keep them away from noise(ignition etc..). I landed all the Analog 0VDC reference signals and the shields to the same terminal block to keep noise to a minimum. Seems to work decent on my hoagie.
I'm thinking about getting the LMA-3 so I can log DS speed, shock travel and have a G-meter.