80 is about right for XP HOME. 125 would be a little high for XP Home OEM.

List price for XP HOME is 199.
List price for XP Pro is 299.

So it appears you are pricing any number of versions. The brutal truth is that there are far too many uncrupolous vendors out there. I don't see any issue here except buyer beware.

There is one item you can't measure. OEM means you get your support from who sold it to you. As such I am free to add any dollar amount I feel like it since you can rightly expect to get me to talk to you about it. That's right, for only 24 billion dollars, I will assure you the best support you can imagine.