Watch out for that. We had a $~6/day reservation for a car in Guanacaste (close to the airport) last year, and it was a bait and switch. When we arrived at the car rental place the rental fee was indeed super cheap, but all of the other fees totaled up to $50+/day.
Just got back and figured I'd report on the car first.
So, yeah, I got the hard sell on tons of stuff: several kinds of insurance, upgrade to bigger car, roadside assistance, tons of stuff. I just kept saying "no, no thank you, I don't believe so". Scare tactics about how tow trucks won't help. What? If the car breaks down, you don't offer a remedy to your customer? Something about distance from an established road. Like I said, hard-sell. Not a pleasant experience, but not horrific either. This was Alamo, btw.
I had printed a letter from Barclaycard with my name and last 4 of credit card number that said they'd do CDW. They said that if
Alamo sold me CDW there would be no arguments, but that the credit card companies will not fulfill their deal sometimes. Whatever, I'll take that risk.
There was one thing they would simply not let me out of the office unless I agreed to it: liability insurance for like $12/day.
The rate of $6/day (rental +taxes) ended up at $7/day, which I didn't argue about. So $19/day, all-in. I kind of expected something like this, so went away about as happy as I could be.
Other expenses with the car: I took the ferry which was $22, and I spent $33 on fuel. Tolls were maybe $5 or so. One toll was $0.18, hehe!
The driving experience was mostly ok on the mainland, even though I got the tiny little manual transmission car. On the peninsula, ah, horrific roads. I was kicking myself for not getting the SUV. I really thought this little car was going to break if I hit a bump too hard, so I took it really, really slowly.
The roads on the Nicoya Peninsula are just plain horrific. There are a few paved highways, but that nice smooth continuous yellow line on the map can go from paved to gravel. Sometimes the paved roads were worse than the gravel roads because the potholes were so numerous and severe that you'd need to go about 10mph to navigate around them.
Here's my most interesting Costa Rica driving story: I ended-up driving at night on the Nicoya. Bad idea, but my plane was diverted to Panama City (weather), and I flew to San Jose the following morning, which gave me a later start than planned. I couldn't get the earlier ferry, so there I was, driving off the ferry at night. Followed trucks for a long time, but farther away from the ferry terminal, traffic dwindled to just me. No problem, I'll just follow the blue line in Google maps. Well, I start down a hill and
the road disappears into a black abyss! The road went through a river! In the day, I might have waded through to check depth, but it was pitch black except for my headlights. So I had to turn around. Luckily only had to backtrack about 10 miles.
When planning a trip, I say "ah, 6 hours, I can drive that", but when I get there I realize it's a royal pain. The alternative was public transport plus taxi's. The folks that went that route were not real happy with their ordeal either. And out at the beach, some people wanted to go somewhere and they rented an ATV, but it cost them $70/day! I was glad to have the flexibility of the car, and despite having to drive the bad roads, and despite the upsell by Alamo, it was still cheaper and better than any other alternative.