The claim is that Judas bought the potter’s field with the money he pilfered from Jesus and the twelve over the years of Jesus’ ministry. He returned the 30 silver pieces just as Matthew says. Upon his death, the land would have gone to someone, a wife perhaps. The priests purchased the field from that individual with the 30 silver pieces.

It still gets called the field of blood for overlapping reasons: because it was purchased with blood money and because Judas’ end there was bloody.

I think it does make a bit of difference. Luke is less likely to use the phrase in a metaphorical way than Peter is. This is because Luke’s remark would be an explanatory editorial comment, whereas Peter’s would be part of his rhetoric.

The phrase could mean “Judas obtained the field as the punishment for his wickedness” and it could mean “Judas purchased the field with the reward for his wickedness”. Both of these meanings are within the range of meanings allowed by the words. But the former clearly involves more metaphorical flourish in the uses of “Ktaomai” (acquired) and “Misthos” (price) than the latter.

Anyway, I think the meaning of Acts is clear. He didn’t just acquire the field, he acquired the field with the money, which clearly means he bought it.

Still, I think it’s best not to view this problem in isolation from this one about the manner of Judas’ death. Judas hanged himself, and after his body had rotted a bit, it fell into the field that the priests bought and burst open. When Peter says that Judas acquired the field as a wage for his wickedness, this is what he meant. He acquired the field because it was his final resting place, not because he bought it.

(I don’t know whether Judas chose that field to hang himself in because it’s the one the priests bought, or if the priests bought it because Judas hanged himself there, or if it was just coincidence/providence.)