1, like you said the product is usually several pieces combined together, may need several sets of mold.
2, you can give the mold manufacturers to do when the offer in their production, general production up to 100,000 then the price of the mold can be ignored. Because injection molding products about 100,000 or more molding profit is much higher than the price of the mold province.
3, the mold belongs to the words, this you can raise their own requirements, because if you molding volume is very small, then the mold is certainly your own, because others give you molding hundreds of thousands of products are not as profitable as the mold is high. But the general mold are their own, you leave to help you molding supplier he is useless, he can only be sold as scrap metal.
4, about the price of the mold, the general humidifier according to the 3 plastic products, the mold price by seven or eight million.