Slightly OT - in need of small metering pump

I'm trying to locate a source for a fluid metering pump; needs to be 12V DC (or lower) powered, suitable for about 0.25ml/min maximum. Most likely type would be solenoid operated with a single stroke capacity of around 25 to 50 microlitres. I've tried the usual places, ebay and a number of surplus places but can't find anything; I can find new but at over $250 it's out of my price range. Anyone know of good places to look for such a beast or, better still, have one for sale? Martin