Thanks for all the suggestions! That banjo brothers one is the closest to matching what I had in my head. It's a bit out of my price range (at least the MSRP is). Ortlieb has some pretty close stuff but again quite pricey.

As for the weight, it's just going to have cell phone, extra battery pack (4 AA's), airzound bottle, and pepper spray. The clothes and lunch I carry for work go in the trunk bag. All the stuff I listed is already on my handlebars area with a clusterfudge of pvc and devices. Not quite as impressive as K'Tesh's though.

I'm not crafty enough to make my own bag but I think I'm heading toward buying one and then modifying it to suit my needs.