Possibly. You still need to know the ratio of silicon to other system parts costs. If a $100 miner is made up of $1 worth of chips, and $99 worth of other parts, doubling the cost of the chips only makes the miner cost $101. Unfortunately I don't know how much the raw chips cost to know if it significant or not relative to total system cost. The silicon could be a significant portion of the total system cost by now. It didn't used to be.
its the goal of the system designer to minimise the system and maximise the contribution of the silicon to the system.. and asicminer have been good at this. their recent systems are quite efficient and their new one, with string support, should be even more so - making most of the cost of the system will be the cost of the silicon. that silicon needs to be extremely cost efficient on a gh/mm basis (which translates directly to gh/$), especially as so many mining asic suppliers are using the same tsmc foundry and similar process, thus their wafer costs are near identical, so the only differentiator is going to be the silicon efficiency of both power and cost. ultimately, its gigahashes per wafer that directly affect the cost.