One of the most expensive, and labor intensive part of mobo development is the BIOS. The licensing is very expensive, and requires a good deal of effort on the part of the SW developer. Often times the developers and mobo mfgr don't even have access to the full source code. The fact that U-boot (universal bootloader) is free makes x86 inherently more expensive than an ARM or PPC board, even if the processor components cost less. This is good for small and mid-size companies that are priced out of x86 development.