This thread was very helpful to me. I didn't know what to buy - I did get a used Zatchels satchel but it was far too heavy for its size (very thick, stiff leather) so I ended up ordering a customized satchel from the Leather Satchel Company.
The Leather Satchel Company's customer service was superb; I forgot to add one customization to my order but I emailed them and it was no trouble to add a note to the order, and they didn't even charge me any extra money (it was just a small thing). My satchel was shipped to me via DHL within a couple of weeks. It is just what I wanted. Great quality leather, great workmanship, and no reason to think this satchel won't last me a lifetime if I take care of it.