Ever since Steve Jobs pulled out a MacBook Air from a manila envelope at a Macworld keynote address in 2008, a few accessory makers have been inspired to design leather manila envelope cases for the Air. Well, we noticed that a company called Maclove has gone a step further and designed a whole line of "Messager" leather manila cases for Mac products.
We had a little trouble finding Messager cases for sale online, but the iPad version appears to cost about $50 (shipping not included). If this style suits your fancy, Amazon does have a number of manila-style leather cases, including ones from Air Mail, Boxwave, Macvelope, and iStorm. They tend to be priced in the $25-$60 range.