Because targets are chosen for activated abilities before costs (such as “Sacrifice Salvager of Ruin”) are paid, Salvager of Ruin’s ability can’t target itself.

Permanent spells that were countered earlier in the turn never entered the battlefield, so they are not legal targets for Salvager of Ruin’s ability.

Salvager of Ruin’s ability can target a permanent card in your graveyard that was put there from the battlefield before Salvager of Ruin entered the battlefield during the same turn.

A permanent card is an artifact, creature, enchantment, land, or planeswalker card.