Probably the biggest factor that affects how much money you'll spend in living in Costa Rica is housing since rental costs can vary greatly from one location to another and depending on the size of the house or apartment. I'll cover the subject of residential real estate further ahead. Some of the information comes from my book Developing and Managing Profitable Rental Real Estate in Costa Rica published a few years ago and I'll treat this subject here with information that could interest you more as a lessee than as a property owner.
At first, you'll probably want to live in an apartment or an Apart hotel until you get the feel of the country. Maybe you'll want to live permanently in one or perhaps you might want a house where you'll have more room and possibly a garden and backyard where you can keep a dog. In either case, it will help you to know some of the rental laws in Costa Rica so you can protect yourself from some not very scrupulous landlords who try to take advantage of a newcomer, especially if the latter is a gringo or another foreigner.
When renting an apartment or house always have a contract drawn-up. In case you don't know Spanish, the landlord or real estate broker will have a draft in English which you can read over for acceptance or negotiation. It must be a true translation of the official contract which must always be in Spanish. In Costa Rica all contracts have a minimum time limit of three years, which can be renovated for other periods of three years each provided that both parties agree.
No landlord can force you to vacate the property during the three years you live in it as long as you pay on time, but you're free to abandon at any time as long as you give advance notice of at least one or two months. Contracts usually stipulate that to get back your guarantee deposit you must give one to two months of advance notice before leaving and that you have occupied the property for at least one year.
Price of the rent can be stipulated in either dollars or the local currency of Colones. If the rent is in Dollars, no annual increase is authorized unless an agreement has been reached by, both landlord and lessee specifying the amount of annual increase. On the other hand, if the rent is in Colones, the law permits a maximum annual increase of 15% over the preceding year. The landlord is free to make any annual increase he wants to as long as it doesn't go over 15%. This increase was established by the government to give the property owner protection against devaluation.