I will be surprised if Mentor finds himself much below $20 at any point hes Standard legal, and I dont think its unrealistic that hes usually in the $25-$30 range, with prices yet higher than that possible if many of the other cards in Fate Reforged dont pan out
Thats where you can take advantage of the infect mechanic
Gamble is another tutor option, but it has a rather risky downside of randomly discarding a card from your hand, including potentially the card you search for
As a Legendary Spacecraft, The Seriema tutors for legendary creatures and, once fully stationed, transforms into a flying 5/5 that grants indestructible to all tapped legendary creatures you control
Bant colors also let you play Falco Spara, Pactweaver, and proliferate spells to take advantage of counters