Erwin,
You actually can't roam into Costa Rica at all from what I've read. If you happen to have a phone that is on their approved list of phones, you have to have it specially modified in order for it to work. Apparently they don't have SIM cards at all. You basically have to rent a phone when you get there.
The satellite service is something for vacation or traveling, not a permanent internet connection method. It's expensive (one week costs the same as one night in a cheap hotel though, plus data charges), but consider phone rental charges, international voice charges, data charges, getting ripped because you didn't read the fine print, gas and time spent looking for a good cell signal near a power outlet, lost productivity because you aren't as comfortable as you would be working from your hotel, etc.
Getting online while traveling is really hard but that satellite system makes it really easy.