JOEL - If you read those Jeremiah scriptures carefully (See references below), and the surronding text, you will see that they are a revelation from the Lord to Jeremiah, to help him with something that was going to happen at that time. The Lord told him what was going to happen in verse 7 and then it did happen in verses 8 and 9. It was not meant as a prophesy that would be fulfilled at some future time, hundreds of years from then. It is only a coincidence that Jeremiah also happens to be talking about buying a field.
In the Matthew 27:9-10 verses Matthew is talking about a prophecy made by someone in the past, that is now being fullfilled. He claims that Jeremy(Jeremiah) said it. But what he is talking about more exactly fits what Zechariah said (ZEC 11:12-14), which was a prophecy about something that was to happen in the distant future; both references containing the same details, such as the potter and thirty pieces of silver. There are no such prophesies in Jeremiah that Matthew could be refering to.
I understand that the word "Jeremy" probably means "Jeremiah", but the word "Jeremy" is what I see in my King James version of the Bible.
In my opinion, the Jeremiah scriptures you quote do not "completely refute" the inerrancy of the Bible. Even if this one example is not a valid one, what about all the other errors I have pointed out? In order to "completely refute" my argument about the inerrancy of the Bible you will have to come up with valid explanations for all the errors I have listed.
I do believe the Bible to be the word of God. It is just as important and sacred to me as our other scriptures. But the Bible was translated, written down, and compiled by imperfect human beings who can make errors. What our church claims is that we have prophets, living today, who can see past the errors and tell us what God really wants us to learn from the scriptures.

Jeremiah 32:6-9
6 And Jeremiah said, The word of the LORD came unto me, saying,
7 Behold, Hanameel the son of Shallum thine uncle shall come unto thee, saying, Buy thee my field that [is] in Anathoth: for the right of redemption [is] thine to buy [it].
8 So Hanameel mine uncle's son came to me in the court of the prison according to the word of the LORD, and said unto me, Buy my field, I pray thee, that [is] in Anathoth, which [is] in the country of Benjamin: for the right of inheritance [is] thine, and the redemption [is] thine; buy [it] for thyself. Then I knew that this [was] the word of the LORD.
9 And I bought the field of Hanameel my uncle's son, that [was] in Anathoth, and weighed him the money, [even] seventeen shekels of silver.

MAT 27:9 Then was fulfilled that which was spoken by Jeremy the prophet, saying, And they took the thirty pieces of silver, the price of him that was valued, whom they of the children of Israel did value;
MAT 27:10 And gave them for the potter's field, as the Lord appointed me.

ZEC 11:12 And I said unto them, If ye think good, give me my price; and if not, forbear. So they weighed for my price thirty pieces of silver.
ZEC 11:13 And the LORD said unto me, Cast it unto the potter: a goodly price that I was prised at of them. And I took the thirty pieces of silver, and cast them to the potter in the house of the LORD.
ZEC 11:14 Then I cut asunder mine other staff, even Bands, that I might break the brotherhood between Judah and Israel.