Not far outside of Banos, you can take the plunge from a bridge. It's certainly not the highest bungy jump, but it gets the job done. The price is around $10. This is just off the road to Puyo, so it can be done on the Banos-Puyo bicycle trip.
Equipment: $10 and extra pair of underwear
As my must-see-tip says, one of the best things to do in Baños is to hire a bike (dirt cheap at about $5 USD per day) and venture into the sorounding areas. Ask around for the best routes. My favorite one was the downhill ride to the jungle.