I won't buy anything from Hong Kong anymore.
I use this one: http://www.ebay.com/itm/Hanna-Checke...item27b5349506
It has a replaceable probe, and mine has lasted years.
BTW, you also need some buffer solution. Get a bottle of 4ph and a bottle of 7ph for calibrating. You'll also want some storage solution, which is the same chemical as what is in the probe. It will help make the probe last a long time.
Keg #1: RHESB 6.2
Keg #2: Cascadian Stout
Keg #3: BMC West
Fermenter #1 Bourbon/Oak Vanilla Porter
Bottled: Mjolnir Mead, Lazy Daze Hefe, The Bollocks ESB, Dark Matter stout.