To get a sense of realistic prices use 1000 piece quantities quoted on electronic component stockists in Guangdong such as http://lcsc.com (or via https://jlcpcb.com/quote#/parts which is a significant subset thereof) and http://hqchip.com (but avoid the red=import results). For a popular component such as a network module, roughly assume chip cost plus 1-2RMB for the PCB, resistors and socket and assembly. Same approach works for microprocessors.