price through several aspects. Among the main constraints is the number of memory slots (as we have mainly 4Gb and 8Gb RAM modules to work with). And 8Gb ECC (ECC/registered memory is the only way to utilize more than 4 slots per CPU) is only recently became reasonably priced (ie. close to 2x4GB). Once the slots are filled with 4GB modules - throw and replace with 8GB. Painful. Once filled with 8Gb modules - replace the motherboard+CPUs. With what? There is of course monsters around - http://www.provantage.com/supermicro-mbd-x8qb6-f~ASUPM3AU.ht... which require monster priced CPUs :)
So, thanks to manufacturers for the cheap 4Gb and 8Gb, yet if they built the large overcapacities for these modules instead of gearing up to 16Gb - that would explain their financial problems.