We are neither Catholic or Protestant, so that does not apply to us. Furthermore, Foxe's Book of Martyrs is a "good read," but that does not mean it belongs in Scripture as God's Word.
Where are the 400 printing press errors? They are in your 1611 version. If you want to read a 1611, go for it, but why insist that there is some sort of religious superstitious power in reading the KJB with the printing press errors in it? As I have already stated, the real reason is because there is a superstitious cult out there that is teaching "1611 only," when some of the KJ translators were involved in fixing the printing press errors.
Being willing to buy his copy from him demonstrates a lot of that superstition, and I'm not sure where you learned all this from, but someone has taught you strange things.