Diablo is dead! But boy did he take a long time to kill. At this point on my AH Barb I think I had 1k more DPS and 3.5k more health and never used a potion. AH-Free barb I used dozens of potions. But Normal Diablo is killable as an AH-Free barb. Talk about patience though.
Gratz on the kill ... on, on to the more difficult ones.
Just another link http://www.reddit.com/r/Diablo/comments/xqpg6/i_finally_did_it_i_beat_the_game_hardcore_solo/
That particular player cleared inferno HC Barb with only 3 AH items. Must have gotten tired or no luck at all in those slots but there is obviously a price to pay to do that, you need to farm a lot to get the mitigation and Vitality gear.
It does show what can be done if you are persistent enough all the same. Not for me though as I do not have that degree of patience.