Pricing just depends on what you're looking for in a bottle and cap. Perhaps provide a little more detail and we can better help you find the bottles you want at a price that works for you.
In most cases, the more you want from a bottle and cap (specifically the cap), the higher the price. As an example, a standard cap without child-safe and tamper evident serrated rings are cheaper than those with them. I know MBV does wholesale and they are $35 per 100 and they come with a child-safe cap, but no tamper evident ring.
Empty 15 ml bottles - Mt Baker Vapor
If you want to go cheaper, going China or buying
buy the case
through an American dealer is really the only way. Either way, buying by the case is going to be in the 900-1,000+ range, minimum, which would be more than you need right now.