Once the Day/Night cycle has begun, if it becomes Day, you transform all Nightbound permanents
Because Aether Revolt has fewer cards, and because we're drafting with more packs of it, you're about as likely to see a specific Kaladesh Common as you are to see a specific Aether Revolt Uncommon , about 10% less likely to see a specific Kaladesh Uncommon as you are to see a specific Aether Revolt Rare , and about 21% less likely to see a specific Kaladesh Rare as you are to see a specific Aether Revolt Mythic
The cost-reduction ability of Sentry Bot doesn't change its mana cost or mana value, only the total cost you pay
With the auction due to run until June 15th, expect that number to only go up.
In a modern world, would it even be played let alone worth more than fifty bucks no matter how rare
That is not a workaround or a gray market