If westereners decide to live for extended periods in Bali, then health cover is osmething to consider.  There are two levels to consider

1. normal visits to a doctor for advice, prescriptions, and occasionally referrals to specialists
2. major problems where one may want to return to the country of citizenship and seek medical attention there
   

Here is a list of options and links that I will add to as I find more.

Bali International Medical Center (BIMC) on the by-pass road near Kuta.

•  membership covers for vists to the general practicioner and then gives discounts on fees for specialists, X-rays etc.  Membership costs about AUD $450 per year for 2 people.
• medical evacuation insurance is available for US$225 per person (about AUD$300)

Promoting Bali

This website has a page at http://www.promotingbali.com/bali-essential/medical-services/ that lists medical centres - there are 4 listed in Singaraja.