Costs in Bali are basically higher than in other parts of Indonesia, with the exemption of maybe Jakarta.
Local food is ~US$1.5-3 per meal, Western food ~US$5.5+ per meal. Soft drink only US$1.5-2.5.
Accommodations, really depends on your preferences, it could be from US$2 for budget ones and US$200+ for high 4-5* hotels.
For specific information you can check out from
http://www.nomad4ever.com/2008/03/17/co ...
Actually all expense depends on what kind of places or attractions you wish to experience.
For Water boom - US$ 65
For Buggy Jumping US$ 75 - 125/ jump depend the kind of jumping.
For water activity - Surfing, snorkeling, para sailing, jet sky US$ 16 - 25/hour
Travellers cheques and cash, preferably US dollars are the favored currency in Jakarta. Credit cards are accepted by higher end hotels, restaurants and shops, but not for day-to-day expenses. In major centres, you can always find a bank that can advance cash on a Visa or MasterCard. Credit card advances at ATM's are possible, but somewhat limited.