Hello Cujo,
I really don't know what the °µÍø½ûÇø population is in Dili at the moment. If I may guess, I would estimate roughly between 3,000 to 7,000, but it was just a wild guess. (In this case, I could be totally wrong. So, don't hold me accountable for the number, OK?) As for the consultation cost to see a dentist here, from what I experienced (and heard) the fees range between US$ 40 to US$ 70. I don't know whether you would consider it expensive or otherwise.
Cheers.