Hm. I'm actually not a crybaby. Let me tell you why.
Because I played this game from day one. The day it hit the shelves I was already testing my necro on battle.net, which now is unplayable because of spambots and hacks, which ruin the online game experience. Not only for me. Just look at the "fix the spambots" topic count.
And don't even get me started on passworded games. It's an inconvenience for me, and I didn't pay for Diablo and LOD for playing inconviniently. I payed my cash for it, I want quality. They are not giving it to me. That is why this game is not worth its weight in cash, for playing online anymore.
Single player is still awesome, though.
That is why I don't recommend buying a new, 20$ cd-key. Because that's what you pay for. CD-key is an online possibility for you, OP. It WAS fun. Up until about two years ago, when I stopped playing Diablo2. It is no more fun.
20 bucks for single player? Nope.
But, if you still want to buy it for the broken battle.net, do it as the guy above me told you to. Be very careful.