FLowmeter with 0-5Vdc output

Hi all,

I am looking for a water flowmeter with 0-5 V DC output.
The ones I found were a bit expensive (like 350-1000$).
Are there any available for a lesser price.
max readable flow should be 40gph. Digital LCD would be great.
Thanks in advance.

Have you looked at

Hedland http://www.hedland.com/

Lake http://www.lakemonitors.com/
I use them for hydraulic oil but they have meters for air and water also