I don't know about the PH part, but Cecil let me use one almost identical to this one
http://www.ysi.com/productsdetail.php?550A-22 Accurate and dependable. Affordable? Well, that depends on your wallet.
But, if you buy one that isn't accurate and dependable, then you're just throwing money away.
YSI is supposed to be pretty good as far as mid range units go. I remember he had to send it back for some reason, but that was probably more that He could not operate the unit.
Mettler Toledo and Hach are the top dogs in water quality analysis. YSI has had a few problems and rank pretty low. Continuous problems with them not working at all. YSI is made in China, where MT and Hach are made in the USA.
Anyway, a pond dude, really dont need water quality analysis equipment!