Before I start answering I will recommend you browse through the "Technology on the Road" posts for satellite/wi-fi/aircard info.  I think you will find your answers.

Both satellite internet and cell phone internet (aircard) plans start at $60/month and so far only satellite has higher end plans available with more speed and/or larger bandwidth limits.   Aircards from everyone (Verizon, Sprint, AT&T) limit you to 5GB/month before they either slow your speed way down or charge you extra, a lot extra for overages.   Verizon just started a buy your own equipment and pay month-to-month for internet plan without a two year contract, still at $60/month.  Satellite and the other cell companies seem to need some kind of contract length. 

The basic satellite plans do not have fast upload, 50-200 Kb is normal.  Cell can have higher upload speeds, but depending on load and location it can also be slow and fast is 500-800 upload.  If you really need better than a high end satellite system with a 1 meter or larger automatic dish is what you need.  Those are over $10K for the dish and $300/month.  How large are those "builds"?

Judy: What davidh is talking about is not your normal usage of surfing and email, he is doing more intense internet operations that use more than the normal retired RVer.  I know people who have used 12GB on Verizon and there are people hitting the 250GB limit on Comcast cable modems.  They are day trading, they are doing software develpment, they are downloading CDs and movies. 

Note that my wife and I use between 2.5 and 4.0 GB per month just doing our normal thing, so 5GB is a bit close for us.