Thanks for the info guys, will check those out.
Which product are you guys talking about? Is it Electric circuit board?
It's a toy, so plastics, PCBAs, microcontrollers, etc.
So toys is a whole other world again from your typical "electronic gadget" as usually the drive to reduce cost is extreme for the maker to keep any margin after the Toys'r'us take their cut.
A typical Chinese toy factory is injection molding + painting + assembly. They don't tend to have any knowledge of electronics whatsoever but just buy in modules for "5-function R/C control" and completed motor+gear assemblies. The factories making those may be in the same town or the town over, just be aware that if you're dealing with a regular toy factory they won't likely be able to do any kind of trouble-shooting beyond "it doesn't work".
If you can afford to give a bit more margin to the factory you might be able to go to a more regular "electronics gadget" factory, but even there they don't usually have any electronic engineers on staff (unless you're talking about the likes of Flextronics / Foxconn but those CMs are not cheap to deal with). Your PCBM and PCBA will always be done in specialised factories (sometimes those can be combined), so no matter what you will be dealing with more than one factory. You can imagine that if you don't have a good insight into how your manufacturing is actually getting done this would be very frustrating.
"The Essential Guide to Electronics in Shenzhen" won't be much use to you beyond how to get a taxi into town (it's more about "how to I ask this shop owner for a resistor" than "how do I pick a reliable factory" but Bunnie's more recent book: https://www.nostarch.com/hardwarehacker might be interesting as it contains some of his experiences getting different projects made.
If you decide to pop over to Shenzhen (I'd recommend that) send me a PM and I'll introduce you to some of the people in the English-speaking ecosystem here.
So do they have some on-stop places, that can handle the entire process - plastics, pcba, purchasing components, quality control, packing etc? Just wondering... If i would like to manufacture 10K pcs of something, is it really possible without going to Shenzhen and running between factories ? And how much would that kind of service cost?
Actually it would be interesting to know, how much would it cost to manufacture 10K pcs of some small gadgets with the bill of materials, say, $25, including plastic parts, pack them and send to US. Like what would out of the door price be?
There are one-stop places, sort of, like PCH. But note that as an example when Bunnie was in charge of getting the Chumby made (quite a few years ago now), he used the services of PCH in the end but was still needed on the ground to communicate the design intent to the people involved in making it happen. It's pretty hard to get around that, as there's a lot of decisions that have to be made in manufacturing something and trying to do it by email is not very efficient. But if the project is fairly "standard" (normal PCBA in a simple plastic enclosure, no need for perfect appearance) it can be done.
It's pretty impossible to give an idea of how much it would cost to produce 10k units of something with a US BOM cost of $25, as the usual process involves trying to figure out what of that $25 figure can be cut down. Which means trying to identify every component that can be replaced with a Chinese-made one, as when you're making 10k units of something it's probably not happening in a bonded facility and import duties are due on every imported component. Typically connectors can be replaced with Chinese-made ones at a fraction of the cost, for example. Which are usually fine, but if you're buying Molex you're paying for fine every time.
Also almost every service / component exists at a range of price points. At the higher price points, you'll get excellent service and a near-guarantee of non-screw-up. At the lower price points you have to be careful to communicate what's essential and expect a certain risk of failure. For example a few years ago I had a plastic enclosure mold made by Star Prototype, who have a British managing director, I wouldn't hesitate to recommend them as they'll work hard to make sure they understand the requirements and get it right first time, but the cost will be several times that of the lowest bidder.
Usually the process goes the other way... you have a target cost and the aim is to figure out how to meet that