Cabs used to be $25 the last time I did that in 05, probably $50 or more now.
Check
http://thebusschedule.com/EN/cr/ they have the CR bus schedules from Jaco to Quepos and back. That route has two buses, one with stops and a "directo". They are quoting the non stop at 65 minutes Jaco to Quepos, maybe optimistically, maybe not, I make it in about an 50 minutes mas a menos by car.
When you get to the Quepos bus station (get off and have a coke) that same bus then continues to Manuel Antonio on the main and only road that Hotel Verde Mar is on--not sure if the Quepos-Manuel Antonio leg is a direct and if he can let you off at the hotel, but if he cannot, his end stop/turn around is about 1/3 mile further from Verde Mar.
But, he should be able to on the way back to Quepos, I doubt that is a direct--talk to him, CR style $$; or cab it from Quepos bus station to the hotel, $5. Bus Jaco to Quepos runs 3 or 4 trips a day, newer bus, not a/c, but not that long of a ride, should run on time, no hills, travel through only one small town, Parrita, and I've never seen slow traffic from Jaco to Quepos barring accidents on that stretch now that the new bridge is up in Parrita and a few other new river creek/stream cross overs by-passes on the way. One non stop leaves Jaco around 11am.
You'll like Verde Mar, and mi amigo Ramon, mgr. Not very fancy, but vry nice and one of the few right on the beach, each room has a kitchen, fridge, stove, coffee maker--bring 8 cup filters from home. If you have time in Quepos, across from the bus station is a mini mart, so get cokes and beer, and coffee, and fruit, and whatever you want for the room, or you can do it the next time you go back to Quepos, you'll eventually be going back and forth.
There is a beach restaurant 100 yards adjacent to Verde Mar, named Baru, very good food from about 8am until at least dark, you'll be spending alot of time there with my friend Memo, the owner, and his brother Manuel, and cold beer or whatever right on the beach, can't beat it.
Tel # for bus company referred to is on that website, but spanish only I am sure.
Talk to Ramon about the best way to get back to SJ when you are leaving, he lives in Parrita so he knows that routine. If you are going back directly to the airport for your return flight, I'd fly Sansa (not Nature Air--goes to diff airport) out of Quepos, $80 and 25 minutes, and just walk a few blocks to the int'l terminal.
PM if I can give you more info on Quepos, I been there a million times. You'll love it.