You get what you pay for so if you go cheap you will get cheap. If this unit is deployed on the other side of the globe and you are using it to determine a revenue stream your better off going with a good system.
FlightCell has a nice system which is easy to install and great functionality and you can use any mapping/tracking solution you want (almost). You have to get the Sim card independent from the unit but that's pretty easy.
SkyConnect and SkyTrac are very similar in build and equipment cost but very in data service cost. Both good systems and they have their own software/mapping
BlueSky is similar to SkyConnect and SkyTrac but the hardware is different and they do have some handheld options. They have a mapping component but IMO not as good/easy as the others.
Your best bet would be to hard wire the power to the aircraft so the unit starts with the aircraft. You need to consider if you want to use Squat switches to signify takeoff and landing or an algorithm of speed and position and that decision may effect the device you would like to use. You can also modify polling rate to suit your needs/costs.
There is a fixed cost per month for most services so even if you don't fly it will run you between $50 to $85 per month.
If you plan to use the Sat Phone at all and your on iridium I would suggest using the gateway to place calls to the aircraft. It's much cheaper. If you plan to have any volume of calls from the aircraft I would also suggest a second unit set up to receive calls on the ground. Sat -Sat is cheaper than Sat to Land.
Also remember that Sat is not 100% uptime, the system can and will go down at times so you will see gaps sometimes in your polling which could effect takeoff and landing. With that, devices can also stop working so it is good to monitor on a regular basis while in flight. If you are using GPS for position the GPS data link can fail or the transceiver can just stop working. Sometimes a power recycle to the unit can fix this but if your system is hardwired that won't be possible.
Sorry for the long post (could have been longer). Hope you find a system that works for your needs!