The Lussac is not available at the LV Boutiques anymore. Your best bet is either Let-Trade or Ebay and they should run about 525.00-599.00 depending on the condition.
They usually have a few Lussacs on Ebay at any given time, but it's hard to find the black. Keep looking though, you'll find it. It's such a nice bag, I want to find one in red.