[raynor]

Check out se4\data\components.txt and do a search for Cloak. It shows a supplies used of 100.

In 1.27 (pre-patch #4), activating the cloaking device did not require supplies, and it didn't consume any extra every turn.

If you have applied patch #4, goto Player Settings and choose 'High Tech' under Technology Level for New Player and start a new game. You should be able to design a ship and test if it uses any supplies for cloaking. Since they fixed the Stellar Manipulation bug where they didn't use supplies, I hope they fixed his one as well.