How to make chalkboard on the cheap
Duraslate will get you a roofing system, so stick to Duroslate if you want chalkboards. 

[walmart, amazon and staples all claim to have those; others do as well.]

Adjusting light positioning, type (possibly adding diffusers) and camera angle on the whiteboard might be simpler/cheaper/faster. Not to mention less dusty.

The paint works fine if done right and can be applied to a piece of hardboard or plywood or even one side of your melamine board (might need to scuff sand first) rather than to the wall. Use a roller for best results.

Surplus chalkboards are dirt-common at every school remodeling project and presumably would be found in at least some architectural reuse (or salvage) facilities.