What type of aircraft? What's your typical flight/trip profile? International? Domestic? What type of data stream/bandwidth do you need? Just sending emails? Hoping for VOIP or streaming video? Web surfing?

All of those things might influence the system and service level you go with. If you're doing all domestic, I'd consider a ground based system like AirCell (That's the same system that the airlines' GOGO inflight internet uses).

If you need international coverage SwiftBroadband or Swift 64 through SatcomDirect might be better options.

I can tell you that based on my own experiences, satellite based internet is expensive! But it looks like you already know that...