Rudy, 9 times out of 10, or maybe 9.5 times, you would need to be the owner to get the data card. Typically you need to show proof of ownership before getting it. On the other hand I have heard some dealers will just order it if asked, and do not ask for proof of ownership. So it will be entirely dependent on who you ask to get yo the data card.
There is no cost for the data card. At least, I haven't heard of anyone getting charged to get one. So unless there is something you think will be on the data card that the owner might use to increase the price, I don't see why it would effect the asking price.