wrong about Dell. how does Dell not have the influence? Dell pioneered supply chain for computers, not apple, and Dell still has more influence.
they sell more total desktop+laptop machines than Apple. Dell does everything by cost bc its customers primarily value cost as the driving feature (large enterprise, federal and state governments, etc).
that's how the auto industry works. if a vehicle manufacturer acted like Apple and dictated the shape and size of every switch, every actuator, every door lock (you name it), then a compact car would cost $80,000. for Apple, their customers don't care about cost so focusing on design with higher costs works very well. for Dell, that would not work well because they would lose the competitive bidding process against HP for enterprise and government contracts.
suppliers are willing to do whatever you, as the assembler, want them to do as long as the price is right. hey man, if you are assembling a vehicle radio and your UID/UIS people don't like radio knobs with increments, but rather wants the knob to turn smooth with an infinite # of angles, then Supplier A would give you a quote of $40,000 for the tooling change. this might raise the price of the head unit by $0.40. multiply that by the number of units you sell and that's your added cost you have to either eat, or increase the price to account for it. eating cost is a last resort, so chances are they will pass it off to the customer in the showroom in the form of a price hike. that price hike then could make or break the competitive position of the vehicle against others in its class
if you are in product development as you say you are, you know that the general rule of thumb is for every $0.10 in cost you add to the product, you add $1.00 to the selling price. this is why Apple's products are so expensive to begin with, which is then pushed up even more to create additional profit margin to account for lower sales numbers. this is why Apple's cash on hand skyrocketed out of control from 2008 until now. their profit margins were set to be based on X sales per quarter. they kept those profit margins even when sales kept doubling and doubling over each other and again after that from 2009, to 2010, to 2011, 2012 etc. Apple is still able to maintain the higher prices despite the fact that electronics (mainly flash based memory and screens) is experiencing a cliff based drop off in prices. eventually though, the disparity between the cost of the components and the selling price will be so drastic that Apple will need to lower the prices