Amed grew as a tourist area because of diving. The small independent hotels are often attached to a dive shop, or have one close by.
The stretch of coastline from Amed to Selang has a selection of dive shops and it can be tempting to go for the first one. Make sure you meet the dive instructor, check out their equipment, and if possible, ask for recommendations from other people. You can check the PADI credentials of a dive center online at www.padi.com, and email PADI Asia Pacific at firstname.lastname@example.org. Experienced diver will be able to tell a good shop from a bad one.
Many of the dive operator in Bali have an office in Kuta / Legian / Seminyak or Sanur. Prices vary a little, but a ballpark rate would be $60-110 for a days diving including the equipment rental. A longer dive session of 5 days or so might cost $90 per day. Feel free to negotiate.
Some of the alternative diving options include kids diving, for those over the age of 12. This is available at Yos Marine Adventures (based in Tanjung Benoa). Disabled divers can dive with Bali International Diving Professionals, based in Sanur. They are members of the International Association for Handicapped Divers. Courses for kids aged 8-11 are available.
Open water courses go for $350-$450 in Bali.