That's why I suggested Bricklink: you can buy individual pieces, rather than entire sets at retail.
There are lots of people who buy sets and part them out for sale there. Since the pullback motors are not very interesting to Bricklink's main market (adults looking for special pieces for their own designs), you can probably find them cheap.
Unfortunately, Lego has discontinued (most of??) the sets that came with electric motors, so the prices on them went up. But there might still be some deals to be found.
I'm pretty sure there are some Bricklink sellers in Asia, so you could get parts without spending vast amounts on shipping.
Ran