It's possible to ISO battle.net credits, however it's illegal to purchase legacy games (including diablo 2).
http://forums.d2jsp.org/topic.php?t=79187663&f=258&p=534524404/
Quote (ytjkxv @ 10 Jan 2019 08:37)
so I would need them to gift it to me?
Due to the cdkey being sent to user purchasing the gift
we will not allow the following legacy games to be requested(ISO) or traded:(...)
You can't trade diablo 2 and some other games.
This post was edited by Wrona on Jan 10 2019 01:38am