Just got PMed about taking the bus down to JACO. Thought I'd share with everyone. I have read plenty of reports of guys taking private taxi's/Vans to Jaco which can end up costing a lot of money. If your on a budget taking the bus is a nice option IMO.
Trip each way averaged about: 2 1/2 hours.
If your "going" to Jaco, take one of the red city taxi's to the coca cola station $2-3 bucks. When you get there ask someone (or your taxi driver) where the ticket both is.The ticket is under $5 bucks. There are some street hustlers guiding people to the different ticket boths. One guy tried to help me but I just ignored him. Turned out he was actually not trying to hustle me just trying to help me and get some spare change. I ended up at the both he was trying to lead me to in the first place. Coca Cola bus station is known to be a dangerous one. Just use common sense anywhere in Costa Rica and you should be fine. I didn't feel "extra" unsafe there or in Jaco.
Buses from San José (coca cola sation): Transportes Jacó S.A. Every 2hrs (6am-7pm)
"Getting" back is even easier. There is a Pizza Hut at the North end of the main road in Jaco (across the street from the best western hotel). Directly behind the pizza hut is the ticket both. Buy your ticket back to San Jose there $4-5 bucks. When you get into San Jose jump in a red taxi (the taxi back to your hotel will be a little more) both times I took taxi's from the coca cola station back to my hotels they charged me more then to get to there. (Even though I walked a few blocks away from the station trying to get a better rate)
Buses to San José: Transportes Jacó S.A., ☎ 2290 2922; 3hr.; 5am, 7am, 9am, 11am, 1pm, 3pm, 5pm; ¢2095
Here's a sight I researched before I got to Costa!
http://www.therealcostarica.com/travel_costa_rica/bus_service_costa_rica.html*One of the hotels I stayed at in San Jose is the Castillo. The staff is really accommodating and will let you leave your luggage in their office for your trips to the beach. I'm not certain, but some of the other "sponsor" hotels, here on the sight will probably let you do the same.