Greg, do you or anyone else have any experience with or knowledge of any of these:

http://www.eseasongear.com/milwaukeesm600.html

http://www.instrumart.com/Product.aspx?ProductID=23681

http://www.mbhes.com/dissolved_o2.htm

The Hannah product doesn't have a price listed but the other two are much less expensive than the YSI and most other brands I found online. I'd like to have a real meter as opposed to a test kit, but my income is pretty sparse at the moment; I couldn't for instance buy the YSI 55 even if I wanted to.