Having trouble linking from my phone, but I paid 27 for a salinity refractometer from the seller "nisupply".
edit, link:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=390192873452
First one was defective as the scale was not level. I emailed the seller and he CALLED me 3 hrs later to apologize, and I had a replacement 2 days later. New one works flawlessly.
Doubt defective units are commonplace, but the 2nd one I received is quality, and his service was outstanding.