This is what three of the leading Greek lexicons have to say on "ἀγοράζω", as used in 2 Peter 2:1
"figuratively: Christ is said to have purchased his disciples i. e. made them, as it were, his private property, 1Co_6:20 (this is commonly understood of god; but cf. Joh_17:9-10); 1Co_7:23 (with the genitive of price added; see τιμή, 1); 2Pe_2:1."
(Joseph Thayer who was a Unitarian and therefore did not believe in the need to even be saved!)
"buy, acquire as property of believers, for whom Christ has paid the price, with his blood, 1 Cor. 6:20; 7:23; 2. Pt. 2:1" (W F Arndt and F W Gingrich)
"to redeem, to acquire for one's self by a ransom or price paid; spoken in N.T. of those whom Christ has redeemed by his blood from the bondage of sin and death. 1 Cor 6:20 and 7:23; 2 Pet 2:1" (Edward Robinson)
This is what I have said the Greek usage of the word means, but leading Greek scholars. It is very clear that the MEANING of "ἀγοράζω" in 2 Peter 2:1, is the SAME as 1 Corinthians 6:20 and 7:23. Only those interested in the Truth as taught in Scripture, will accept this and stop trying to put personal doctrine above what the Word of God actually says.