Here are some other money-saving tips:
1. Hand launder lighter wieght clothing, including socks and underwear. A 3-ounce travel size bottle of Woolite or Wisk is perfect, and is enough to do several items by hand in your lavatory sink.
2. Rather than paying "por pedazo," get your laundry done by weight ("por peso"). I know of at least four lavanderias within walking distance of the Gulch, including Sixaola (near the Gran Hotel C.R.) and Lavanderia Camila (across the street from the Soledad church on c. 9, two blocks south of the Presidente). Neither of these is the cheapest, BTW. While walking/busing, look for hand-lettered signs reading "Lavanderia" or "Se lava ropa." You can often get 4 kg. of wash done for under 1500 CRC
3. Dicker and hagggle: Yes, you need Spanish. Anywhere along the mercado Central or at the feria agricola south of the Gulch, you can get ridiculous deals by haggling. I don't think it's so much "the gringo gouge" that costs us extra money as it it the unfamiliarity of haggling and striking a bargain. This can also be done with the chicas (see below)
4. Not all working girls in C.R. are obvious, and 80% of them never visit our favorite bars and MPs. Particularly near the end of the month, a gentle smile and inquiring look can connect you with a "non-pro." Like everybody else, pretty women often need to pay the rent, and even if she doesn't label herself a prostitute, she will rent it to the right man. Spanish absolutely required here. Look for these girls at paradas for buses going to Desamporados, Alajuelita, Pavas or other poorer parts of town.
5. Particularly if you have a favorita/repeat provider, you can often strike bargains with her. Believe it or not, beyond professional pride and a dearly-held price point, many of these ladis have a sense of justice. Explaining that the drinks/meals/gifts also have value, reminding her how good the sex/affection has been etc. can turn a $80.00 hour into an $80.00 TLN. I've done it with amazing ease. I even had a provider this last trip offer a freebee, simply because she had to cut out of our first session together to answer a family emergency. When I explained that a free session would not be fair to her and offered 20K CRC, the "make-up" hour turned into a three hour party.

Work the cultural love of bargaining to your advantage.
6. Steak? Burgers? Lays potato chips? Forget that shit until you return home. Honestly, you'll save money by eating the fish and local produce that the ticos eat. This was mentioned by BKTuna above, but it bears repeating. Save your pizza cravings until you get home, but enjoy the cheap seviche, tortillas, plantanos maduros con queso etc.
6a. Water: I spent a ghastly amount of money on bottled water during my recent trip. In fact, this isn't necessary. The local water is perfectly safe to drink and doesn't taste bad (depending upon locale, of course). If you're concerned about water safety, buy a 1 liter filtration bottle (Wal*Mart, $6.95) to drink with greater peace of mind.
6b. Drink locally. Forget American brands, switch to rum instead of whiskey or vodka. Try guaro (Casique is a good brand and very inexpensive). Guaro and Fresca is a delicious drink. If you insist on Jack & Cokes or Grey Goose, you're going to spend more money than you have to.
I think a fun and interesting part of travel is to at least try local foods, drinks and customs. If you're spoiled and "must" bring your foo-foos, Arabica coffee, Maker's Mark or whatever habits with you, you'll pay for the priviledge. In my view, guys who refuse to leave McDonald's and Budweiser behind in the U.S. are missing part of the fun of travel...just MHO.