Recently, I have seen a lot of confusion regarding the in game monetization for Diablo 4. Just prior to the server slam, the developers did a live stream clarifying a lot of points and also confirmed that would be there last developer dep dive until launch, meaning we are unlikely to get any last minute surprises at this point.
The list below contains everything you are likely to be able to purchase beyond the original $70, that we know of at this point in time. For each entry, their benefits and price will be included, if known: