It depends on a number of factors. Firstly, are you a walk-on, i.e. have your own kit or a rental customer using site kit. In UK prices, the equivalent of $5 is cheap if you are a rental customer. Secondly, if you are buying by the 100 then you are looking at a decent price but if you are getting them by the 1000 or 2000 then that's a bit expensive.
Third factor is that both Tortoise & I are thinking in UK prices here. I would imagine that Indonesia has a much smaller marker for paintball, which means it costs more to import paintballs as they are getting much less into that country so they would be more expensive. We also have no idea about the import costs or tax status there.
Taking into consideration the fact that you talk about cost per 100 & I gather you are new to the sport & therefore probably a rental player, I'd say you are getting quite a good deal all in all.