Can a spell with buyback be countered and still have buyback applied?

Buyback is a keyword ability that modifies where a spell goes when it resolves: instead of going to the graveyard, it returns to its owner's hand. This is governed by CR 702.27a, which specifies that buyback only affects the spell's destination upon resolution.

When a spell is countered, it never resolves. Instead, it is placed directly into its owner's graveyard as a state-based result of being countered (CR 608.2b and CR 701.5a). Because the spell never reaches the resolution step, buyback's replacement effect never gets the opportunity to apply.

It's important to note that paying the buyback cost is done at the time the spell is cast (CR 601.2b). So a player may have already paid the extra buyback cost when the spell gets countered — that mana is simply lost, and the card still goes to the graveyard, not back to the hand.

Example: You cast Whispers of the Muse paying its buyback cost of 5 mana. Your opponent casts Counterspell targeting it. Whispers of the Muse is countered and goes to your graveyard — the buyback cost you paid is wasted, and the card does not return to your hand.

In short, buyback only matters at resolution. A countered spell never resolves, so buyback is irrelevant regardless of whether its additional cost was paid.