Eric Stevens
They all come with one set of ink cartridges which have been partly depleted by the need to fill the system for the first time. Th $/ml for the 4900 is less than for the other two so the first charge costs less than it does for the others.

PeterN
Nope. IIRC the 4900 comes with its cartridges filled to the same amount of ink that as in a purchased replacement cartridge. The other cartridges are about 25% of that figure. However, if we agree on the principals, than we simply need to see where the facts fit in. The methodology for measuring cost is the important point of agreement. If we do not agree on the methodology, I am receptive to what you have to say. If my above assumptions are not correct, I stand corrected.