We bought a really good in-car fan today for £2.99!!! it runs off the cigarette lighter connector,luckily we have one of these connections in the rear of our Peugeot too :D we got it at Lidl's.
We already have another one,we got from a car wholesaler and that cost £20 plus a battery operated one,for when the car engine is not running.Just thought if anyone was looking at the possibility of buying a fan this info may prove useful ;)
Jacqueline.