I love the show but I'm not sure I really want a third season... I thought they did a very good job (as well as they could) with that finale, so a third season could kind of undermine that. The main problem is the budget. If it were to get a third season, the budget would have to be lower, but the development of the storyline in the finale requires a higher budget or more restrictions on storytelling. And they can't just have John go back to 2009 and Sarah because that would be... Stupid.
I'll buy the blu rays when they're out here, and if there is a third season I'll get with it, but I'm not helping some campaign from people who can't just let some things go. I'd rather see Dollhouse get a second series, or at least a chance to end as it wants.