How much does the Costa Rica entry cost?

There is no government fee. No entry fee. There is a departure tax, usually bundled into your airfare.

How long can I stay with the Costa Rica entry?

Up to 180 days, at the officer's discretion. The authorization itself is valid: Per visit.

Visa-free entry · Central America

U.S. citizens can stay in Costa Rica for up to 180 days without a visa, provided they show proof of onward travel.

Short answer

Who needs the Costa Rica entry?

No visa required for tourism. The length of stay is set by the officer at the border.

No government fee. No entry fee. There is a departure tax, usually bundled into your airfare.
Typical processing: Stamped on arrival.
Maximum stay: Up to 180 days, at the officer's discretion.
Passport validity: Valid for at least one day beyond arrival, but six months is strongly recommended.
When to apply: No advance application required.

Migración
Dirección General de Migración y Extranjería
Open the official form
Health
Costa Rica entry requirements (Instituto Costarricense de Turismo)
Open the official form

1
Book onward travel before you fly
Airlines and immigration both check for a ticket leaving Costa Rica.
2
Ask how many days you were given
The stamp can be less than 180 days — check it before leaving the counter.
3
Leave or apply before it lapses
Overstays are fined $100 per month and can bar re-entry.