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I got an iPad 1 neoprene sleeve for cheap when I got the iPad 2 which I use with a Smart Cover. Any sleeve will fit so I would suggest looking for any sleeve, not just those specifically made for the new iPad. If you check Amazon for "iPad sleeve", you can get some good deals.
 

what about incase sleeve that fits over a smartcover

Completely agree with waterfield (sfbags.com). Excellant quality and customer service. I have had the slip case for two years and I just ordered the smart case for my new iPad. They have a different size for if you have the smart cover or not.

Just a note, they are currently sold out of the smart case because of so many new orders, but they said it will only take a week to make mine.
 
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I just bought an M-Edge Touring Sleeve and I plan on putting my new iPad with Smart Cover an back shell in it.
 
Completely agree with waterfield (sfbags.com). Excellant quality and customer service. I have had the slip case for two years and I just ordered the smart case for my new iPad. They have a different size for if you have the smart cover or not.

Just a note, they are currently sold out of the smart case because of so many new orders, but they said it will only take a week to make mine.

I agree. Got the Waterfield Ultimate sleeve in the mail several days ago. Impeccable materials and build. Looks like there's room for a thin shell case. Waiting for my Incipio Lexington to ship.
http://sfbags.com/products/ipad-cases/sleevecases-ipad.php
 
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