Here's a 12VDC marine fresh water pump (larger than the Edmund's, but cheaper - and DC):
http://www.defender.com/product.jsp?path=-1|51|299222|121271|826345&id=961700
You might try contacting this company of miniature pumps:
Don't expect them to be cheap, though.
One other possibility (though probably not as small as you want) would be a windshield wiper washer pump; they run off 12 VDC, and are very powerful for their size (the motors are pretty high current). You could probably find some serviceable ones at an auto salvage yard (or other auto parts places).
