So the extra heat sink reward was worth 3500 credits, 1 Mechanical Scrap, 1 Niobium, 1 Vanadium and gave a module that isn't even best in slot.
Some CGs don't even offer beyond credit rewards

but I'm also aware of people who'd pay tens of millions for 1 Niobium (let alone polonium)... end of the day the point of a CG is in the name; the community goal. Although I'm no FOMO bunny, but CGs which reward unique, sometimes best-of- field equipment as one- off rewards is relatively bad design from a player perspective.
Anyway, as soon as you start measuring rewards like this, you realise how busted the game's economy is, because it all stops making sense.
Personally, i see a reward of an engineered module that doesn't even require access to the relevant engineer to be far more valuable than, say, a 50% discount on rank- locked ships... but nobody has really complained about ones like the latter despite credits growing on trees.