On ebay............. for about £250

Only joking mate, you can pick up genuine ones for about 30-40 quid, just keep an eye out on these forums for boys breaking 4x4 safs, the only down point about genuine ones is that saf bonnets with vents go for about £150-£200 , so unless the sellers bonnet is badly marked or accident damaged, he's unlikely to split it and sell just the vents. Alternatively you could buy replicas from any aftermarket car accessory firm, again price will be about £40