I do a lot of work with accelerometers, so let me give you a little insight...
A GOOD (not great, not bad) 30+g accelerometer will run you $500 for a 3 axis. Now that's just accelerometer's alone, which will not give you enough data to get a flight path (since accelerometers are affected by rotation, you need to take that into account, along with the gravity vector). You will need a 6 DOF unit. I have one from MemSense sitting on my desk that cost $2500, and even it doesn't produce data "good" enough to get a 3-D position from.
The ONLY 3-D "grade" accelerometers out there are made by companies like Honeywell ($20,000), Northrup Grumman ($50k+), Sperry Marine ($50k), L3 Communications ($50k+), L3 Communications, etc.
I'm not saying its not possible to get 3D position with low grade accelerometers, but don't expect a lot of accuracy, and expect to work for MONTHS on the multi-dimensional scented extended Kalman Filter to track all 6 degrees of freedom. If you do get one working, start a company and sell it, you can see from above, its a small market and is very expensive.
BTW, the reason that those are so expensive is that they use fiber optic or motorized gyroscopes along with very sophisticated (and large) lever-arm accelerometers and huge filtering algorithms.
I'm working with an ADIS16350 right now thats a +/-10g, +/-300 degree/sec, 6 DOF accelerometer/gyroscope, its shelf cost is $550 and is a 12 week lead time (although I think Digikey has some in stock right now). I'm hoping to make a 1-D position sensor out of it (only care about up/down motion but needs to be accurate to 2cm), on a ship that also experiences yaw/pitch/roll/surge/sway/heave. I'm 2 months into development and I've yet to have anything working, my Kalman filter seems to diverge very quickly, and its only accurate for a few seconds.