Try Seagull out of Columbus Ohio. http://www.seagullbags.com You can customize to your heart's content (and your wallet's too). The buckles can be done in a lightweight, but extremely sturdy, metal to solve your brittle buckle problem and the canvas is top notch when it comes to downpours. They are super easy to work with (though their lead time is several weeks). They are made in Columbus by a great crew.

Hope this helps.