Is it possible to create a voltage divider without resistors?
1) That is correct

2) I would want a fairly stiff supply there so would recommend keeping the buffer opamp. Without it your potential divider won't maintain half supply voltage if there is any loading.

3) TI make the tle2426 'rail splitter' IC, which has the same function you want but a minimum voltage input of 4 V. I doubt you would find anything specifically for that function cheaper than a pair of resistors and an opamp.