I have a small condo in Tamarindo, which is about a 45 minute drive from Liberia. The temperature is very consistent (hot!) and the people are friendly. Quite a few Canadian and American expats here. This is a beach town on the Pacific side - you can manage here quite nicely without a car; walk to the beach, the stores, restaurants. Real estate can still be purchased quite affordably if you are content with a smaller apartment/condo, but prices are rising. Rentals are cheaper during the tourist down-time. The rainy season is about May to October, but the rain here is once every few days for an hour or two in the afternoon or evening - doesn't much affect the temperature. Generally 28 - 34c. (80-90 F) all year round.
Cost of food in grocery stores is not much cheaper than at home. The farmer's market once weekly is a good place to buy fish, fruit and vegetable, which is all I really need. About $10 a day covers it for me. Restaurant meals can be as expensive as home if you go to places that cater to tourists on the main drag. But if you wander around to the smaller places, it is much more affordable. The water is clean here and you can feel safe drinking it right from the tap anywhere here.
If you wanted to come here for a month or so, it's easy to walk around and find a cheap hotel to stay at until you get your bearings. It wouldn't be fancy, but no need to book on some internet site and pay much more than is necessary.
Liberia is the nearest airport, although Tamarindo has its own little airport where you can get a flight to Liberia or San Jose. Liberia is fine, and has the usual city-living stuff, but no ocean!
Wherever you choose, it's a good idea to spend a bit of time and see how a place fits for you There are cheaper places than Tamarindo, but, again - if you get a bit familiar with Tamarindo and rent a car with GPS, you can drive around and look at various small locales and see what you think. The roads in Costa Rica are not what you are likely accustomed to - a lot are narrow and unpaved and full of holes. Even the main highways are single lanes and curvy with a maximum speed of 80 k - about 50 mph. On the other hand, where would you be going in such a hurry? If you just relax and expect that going anywhere is an all-day event, it works.
That's about all I can think of - Tamarindo is my choice and I love it here.