Reddit mentions of iGaging AngleCube Digital Level + Bevel Gauge 2 in 1

Use one of these: https://www.amazon.com/iGaging-AngleCube-Digital-Level-Bevel/dp/B002LL0BIC

Use a precise ground bar across the outer rim to set 'level' (or even better, mount it level in a vice with a machinist level), then use the digital angle cube. Should be accurate to ~12 minutes.

Alternatively if you need more accuracy, mount it in the mill vice, then run a 10ths indicator along the distance. Record measurement at a '0' and at the end (but measure travel). Do the math. Do on both sides of the center and you don't even have to make sure you've mounted it correctly in the vice, since the average of the two will be the proper angle.

What kind are you looking for? Something like a T-bevel? Or a digital level? I've got both, and they work fine for their particular applications.

These things are surprisingly accurate too:

http://www.amazon.com/iGaging-AngleCube-Digital-Level-Bevel/dp/B002LL0BIC

The Cloudbait link works for me (I was able to get there from your post), so I'd just try it again, although the cached copy is basically the same.

Cost breakdown for just the tracking mount:

• Mechanical hardware (wood, aluminum, nylon, delrin rod, screws, threaded rod, etc.) was roughly $30
  
• Ball Head, $20
  
• Breadboard, $25
  
• Battery, $40
  
• Power leads, $5
  
• Microcontroller board, $20
  
• Motor, $15
  
• Angle block for calibration, $25
  
• Motor Driver Board, $20
  
• Misc bulk components (LEDs, headers, microswitch), $5
  
  So, a little over $200 for everything, although there is definitely room to save depending on what components you get and where you get them. Still is about half the cost and more flexible than a comparable commercial product like this, although mine doesn't look quite as elegant. :)
  
  The entire thing is also mounted on a $200 tripod head and a $200 tripod, but you could get away with something an order of magnitude less expensive--I already had the tripod equipment, so it wasn't an added expense for this build.

https://www.amazon.ca/iGaging-AngleCube-Digital-MiniMag-Level/dp/B002LL0BIC

Woodworking/Metal too I guess: iGaging AngleCube Digital Level + Bevel Gauge 2 in 1 https://www.amazon.com/dp/B002LL0BIC