I ended up booking the Costa Rica Shuttle. I arrive in SJO at 11:30 a.m. So rather than wait at the airport, I'm headed into town and the shuttle will pick me up at La Amistad at 3 p.m. to go to Jaco. I am returning to San Jose two days later on the 5 p.m. shuttle with pick-up at my hotel. The cost each way is $30. With a group you might find private transportation that make more sense. But for me, this sounds like it will work fine. Will report back on my experiences.

Actually that would be $30 PER PERSON. Since there is you and your chica that would cost you $60 total each way. And since you have to head into town and wait to be picked up at the Amistad that could be another $20 for you to get into town or $80 total the day you arrive. If SL Kelvin can pick up your chica for you, he probably drive out with her to meet you at the airport as soon as you get through customs and then you all could drive direct to Jaco from there, all for only $10 more than it would cost you the way you're currently proposing it PLUS you could get to Jaco by 3:30 or so in the afternoon instead of 7 in the evening. And you could still use the shuttle if you want for the way back to SJ 2 days later. That's just another way to consider.