Temperature, Humidity etc. indicator.

Good day to all of you!

I've been curious- if there is any thermometers or something like that, that shows more stats than temperature+humidity? I'd been suspicious that my ladies are low on CO2, but dunno how to check that :S

Look for the autopilot, its about $100 it gives u temp, humidity, and co2 monitor.

I have found this one (http://www.ebay.co.uk/itm/Digital-3-in-1-Ph-MeterPen-With-Thermometer-And-Relative-Humidity-Meter-/130958383042) in ebay- anyone ordered these or similar from ebay??
Want to know any reviews- are they worth the money?
Or maybe you can suggest some better ph meter <50$?