if you assume, on average, you're drafting 31 playables for your deck (23 spells, 5 lands, 3 sideboard cards) then approximately 10% of your cube could potentially be strong sideboard cards and the resulting decks would be 'more powerful' than a cube with no sideboard cards
Elvish Spirit Guide sees play in the popular Legacy Belcher deck
The TCGPlayer app has a scanner to quickly identify cards and pull up market details
The Admiral Brass, Unsinkable display commander is printed with the foil-etched treatment on a thicker cardstockgreat for showing off your commander but not legal for play
This, however, is not the appeal of Animar
I have played (on the draw obviously) Blackmail and had it be better than a Coercion (they had a land I could take!)