Decent push cooling fans seem to cost a fortune, and the cheap 80 watt units some sellers are hawking are as much use as farting into the grill.

I scoured and found range rover air con fans fit the bill, powerful and cheap, they come in pairs, but for a single theyre easy to modify, and you end up with a spare.

Like these - LAND ROVER RANGE ROVER P38 4.0 LTR V8 4.6 V8 TWIN AIR-CON ELECTRIC FAN

[Edited on 6/3/17 by r1_pete]

Land rovers are a really good source of decent cheap parts. I use the v8 disco intank swirl pot and pump, brilliant and cheap. This looks like another example.