Yes, at least here in the states flow meters are easy to come by.
Joe would have to pipe up with the exact model number of the flow meter he used, but according to his review it was a really nice Swiss flow meter that puts out a tach signal just like a fan. He said it was a bit over a $100US in his wb review. You might be able to find it for less over there, since it is imported to the US from Switzerland.
On the lower cost side you can get inline flow meters for about $45 US that you read directly off the side of the gauge. They are more flow restrictive than the one Joe used, have to be read by eye, and not as accurate, but less than half the price. For an idea of this type of flow meter go to
http://www.McMaster.com/catalog/108/html/0444.html and scroll down to the 3rd group of meters, the Acrylic Block flowmeters. A 1/2 NPT meter that'll read 0.5 to 5gpm is $47.