Digital Hygrometer Thermometers

I am looking at getting some Digital Hygrometer Thermometer for my cages. My questions is this. Should I have one for every tub and if so where can I get a good deal on 10 of them?

One for every tub = gadget overload.
Unless you are trying to maintain vastly different environments in different tubs, save your money - the differences won't be that extreme tub to tub, and you should be able to recognize the different conditions without seeing actual readings. I recently bought a few small ones, just to see how much difference a few changes would make (I already knew it was REALLY DRY). If you are concerned about humidity in your racks, the easiest thing you can do is to use a substrate like mulch, coco-fiber, etc. (I'm not a huge fan of misting over paper or aspen).

WalMart (and any number of other stores) have a range of digital hygrometer/thermometers, ranging from about 6-7 dollars and up. For my purposes, the cheap ones are fine; as I don't really care how accurate they are (it doesn't matter to me if I put two of them side by side and get readings of 50% and 56%). I use them as a basic reference, a trending device. For those that are more focused on specific and accurate numbers - and, for some species, that is certainly warranted - it would be worth researching the devices...and choosing models which have demonstrated accuracy and consistency.