I wonder how much has changed - I visited back in '07 and felt like Costa Rica was incredibly affordable, although I've heard it's gotten more expensive as it's gotten more popular. I ate plenty of casado plates for about $3, stayed in some (quite rustic) places I think as low as $15/night, traveled between towns via public bus for a couple bucks per trip, etc.

Although, after suffering through a few long, hot, cramped bus journeys, on my last day I booked the Grey Line tourist van for the first time on the trip - I got a ride directly from Tamarindo to the San Jose airport, in air-conditioned comfort, for like $15. It took like half as long as the public buses would have, and it was comfortable, and I didn't regret making my travel "less authentic" at all.

Oh, it looks like the place I remember being $15/night is now up to $26/night, although I think they've spruced it up a bit too: https://www.losminerosguesthouse.com/losminerosguesthouse-1