Lost Planet also had a second edition with all new achievements, if I'm not mistaken. I don't think this game is going to this time though.
I have BAC vanilla, and I don't really care to pay for some of the DLC offered for it. It's nice, but aside from Catwoman, which I got with the game, I've heard none of the other characters are playable in story mode. I understand the challenge maps are pretty similar, and the game is absolutely phenomenal and fun to play regardless of what mode it's in. But there's something about the challenge maps being separate from the campaign that makes me less interested to play them... much less paying more to do so.
However there is a bundle for all the DLC thus far for 15 bucks, which saves a little money, I believe... and if it went on sale that'd be even better. If they throw out a new bundle with the Harley Quinn DLC for 20, I'll probably pick it up eventually, even if I wait for a sale to do so. Otherwise I might just buy the Quinn DLC, since it's more story mode goodness.
I wonder how they plan to include Robin in the story mode for it for those who didn't buy his pack though...
Anyway, I'll say again that the game is one of the best this gen, and has plenty of content to be worth it even without the DLC. Kudos to those with the patience to wait this long and will be finally sinking their teeth into BAC awesomeness.