Thought I would give you a rundown on the options...
Iridium is good for voice and limited data - you NEED to use compression services to make this cost-effective. OCENS offers weather and email services that are designed specifically for this type of use. With our email service you would see around 6-10 emails per minute of iridium airtime. This would vary depending on the attachments - but this number is based on average emails.
The Fleet 150 would be a great system for what you are looking for as the voice airtime is pretty much the same as the Iridium, but the data is MUCH cheaper - not to mention WAY faster. If you do the math the Iridium comes out around $75 per megabyte vs. the FB150 at around $13.50 per megabyte. And this system will let you surf the web! OCENS email and weather services can save you $$ here as well by compressing the data and reducing the amount the goes through the system.
Another option is a portable BGAN system. This unit offers the same highspeed data and voice as the fleet but with lower airtime costs, and the equipment starts at only $1495 vs. $6500(for the FB150). The only drawback is that you have point this little guy (bout the size of a small laptop) at the satellite - thus your platform needs to be stable. But for the cost it can be a great complement to any communications setup.