agreed. however i'm not sure that such a combo product exists.
you could buy a normal wireless keyboard with a trackpad that runs off of battery and it would only cost you perhaps $1 every 6 months for batteries (or less) and you can buy it for cheaper.
or go with a wireless mouse and keyboard set instead since just about all the trackpad keyboards do not have any real adjustment for sensitivity and the logitech ones are known to revert settings back to default even after you changed them.
not the answer you were looking for but i think that might work out better for you.