Anyone know where to get one?

Knowing the water temp would help a ton since I don't have a fish finder

I'm desperate and having one would be great!

On the boat, I do use my fishfinder but while I'm shore fishing I picked up a cheap pool thermometer for wal mart. Probably not dead On accurate but gives me a good idea on the range.

I've been using a specialized fishing thermometer for several years now; it is protected by an aluminum tube so it won't break while storing, carrying, or using it.  It is similar to these models:

 

BPS

 

Cabelas

Local fly fishing shops will have them too. I keep one in my livewell that I used to carry on the creek. Lets me know whats going on in there. Im surprised that fish finders havent added and extra sensor that can tell you livewell temp.

I use one from an old aquarium. It is an electric model with about 2 feet of wire that you dip in the water and it reads the temp instantly in  fahrenheit or degrees celsius. It is only 2 inches wide or so and runs on a button battery. You should be able to get it at any pet store for a couple bucks. 

I use a "stream thermometer", as shown in Goose52's BPS link. In stores, if they have them, they're often in with the fly fishing supplies.

Look for a Luster Leaf PCPS50 Pro-catch Plus, it's electronic, you can find a thermocline with it.