How much will Harry Potter Midnight Premiere tickets cost?

I've never been to a midnight premiere soo...

Since it's in 3d - estimation- how much do you think it will cost?
Should I buy my ticket in advance online?
If i buy the ticket online, I don't have to wait in the hugeeee line
right?

I'd appreciate any tips - I'm the biggest fan and would hate to miss
the first part of the movie because I'm stuck in line!