Where can I find a guinevere?

I doubt it's available online except for ebay or a consignment website. This is an older style and was at the outlets last summer so it's definitely not in stores anymore. The only other place that may have it would be the MJ boutique, but you'd have to pay full price for it. Good luck!
 
^ I forgot about bluefly!

Outlets such as Nordstrom Rack, Off 5th, and NM Last Call. Some sightings of MJs have also been at TJ Maxx at select stores. Online websites include bluefly.com, smartbargains.com, and overstock.com. Definitely be careful though, after you receive the bag confirm authenticity because these locations can sometimes carry fakes due to bait and switch or unreliable third party sellers.