They go for about $250 US. It measures temps (in C or F), nutrients (in EC, CF, or PPM), and pH. There are a few reasons I went with this particular unit. First is the warranty - the unit carries a FIVE YEAR warranty. The pH probe itself is warranted for 6 months. Another thing I liked is that it uses separate probes for temp/nutrients and pH so if the pH probe needs replacing, that's all you're replacing if your temp/nutrient probe is still operating properly. Lastly, the opinions on this forum convinced me it was the way to go as opposed to buying three different meters...or even buying the Hanna or Milwaukee combo meters, both of which use a single probe for all functions and have a shorter warranty.
Anyway, I'm absolutely thrilled with it. It's extremely easy to use, extremely accurate, and their customer support is top notch - I called them before I purchased the unit to ask them a bunch of questions and just to get a sense of their customer service quality. Even assuming it only lasts exactly five years when the warranty expires, I think it's money well spent considering the cost and warranty lengths of the smaller single-purpose meters.
You can check it out here:
http://www.getbluelab.com/shop/Bluelab+Combo+Meter%99.html