What budget to travel à Bornéo? Money and currency

Indonesia is a cheap destination where you can stay in very good hotels for much lower prices than in France, including luxury hotels. But beware of cheap accommodation where comfort is sometimes very, very spartan, so don't hesitate to pay more. It is easy to exchange and cash payments are preferred, except in the most tourist sites where you can often pay by credit card. Tipping is not mandatory.

What budget for activities and outings à Bornéo?