Or more accurately Cheap Chinese Toy..
 
They're about $5 from eBay with 'buy it now'
Got mine for $3.25 because there was actual bidding involved.
 
It's actually worth $5 (or better yet $3.25)
 
 
Just search for Inclinometer on eBay
 
The base can be mounted at any angle (upside-down), just twist the front ring that has degrees on it.
 

 
 

Didn't post until I got it.......

It works, doesn't look like it will stop functioning.

It's something you'd get at a Big Lots store if they had them.

Quality wise, what do you expect for $5?   (that's total, shipping included)


For scale, the bottom of the base is 2" across, and it's 3" tall

I have the same exact one and the stock one. This one is a cool toy..no real use except for decoration..same thing for the stock one too 
Anyways its very sensitive to bumps compared to the stock one so be prepared to use it for no real purpose

Or you can use a string, and a small super ball, and hang it off the rearview mirror.  All of .25       



Just thought I toss that out there since you were talking about on the cheap!!  I do have a factory Toyota inclinometer. 

I couldn't figure out how to attach protractors............

That's a nice little inclinometer.     I'll have to get one and try it for myself how it works. Though seems cheesy?? but its better to have something rather than nothing and for only 5 bucks!