There is no contradiction about who bought the potter’s field in the Bible. It was the Jews who technically did the purchase, but they did it in the name of Judas which is why it is attributed to Judas.
The Jews (Matt. 27:7-10) – “And they counseled together and with the money bought the Potter’s Field as a burial place for strangers. 8 For this reason that field has been called the Field of Blood to this day. 9 Then that which was spoken through Jeremiah the prophet was fulfilled, saying, “And they took the thirty pieces of silver, the price of the one whose price had been set by the sons of Israel; 10 and they gave them for the Potter’s Field, as the Lord directed me.”
Judas (Acts 1:18) – “Now this man acquired a field with the price of his wickedness; and falling headlong, he burst open in the middle and all his bowels gushed out.”
The Jews bought the field in Judas’ name, on his behalf. It was with the money that had been given to him for his betrayal of Christ and was the same money he threw back at them. The Jews could not use the money since it was blood money and they bought the field in his name. This is why it says that Judas acquired the field.
It would be like me giving money to my daughter to buy an apple at the store. It could legitimately be said that I bought the apple since I gave her the money with which to purchase the fruit. Also, she is the one who actually purchased the apple. This idea is found in the Bible. For example, In John 19:1 it says, “Then Pilate therefore took Jesus, and scourged Him.” But we know that it was not actually Pilate who did the scourging. Rather it was he who handed Jesus’ over to the Roman soldiers to be scourged. They carried out his orders.