At Limon, Costa Rica there is a Red Tent area on the pier. They have a sign displayed with the tours and the prices. Thus no Haggling! We took the Tortugera Canal and Banana plantation tour. There were 4 of us in a private car. We stopped at a beach, took the canal tour, walked through and witnessed processing at the Dole Banana Plantation, stopped for a photo opportunity of various vegetation and a 3-toed sloth, plus our driver took us to a local supermarket so I could buy coffee. Price was $30pp and included the canal tour but not tips. It was great.
If at Puentenaras, Costa Rica we took the ship's tour for lunch and rafting on the Coroboci River. It was a great way to spend the day and not adventurous at all accept for the fun on the river which will just get you wet!