Here's a pic or two of my Work In Progress feed bag. Basically I've taken a £2.99 clothes line peg bag from PoundStretcher, sewn in a couple of velcro straps and used an old Bontrager SyncV2 light clamp I had lying around. It's not finished, I think I need to move the velcro straps about a bit, as when there's weight in it, it seems to sag under the handlebars. This doesn't happen so much when there's a dry bag strapped to the bars, but it would be nice to used the feed bag on it's own.
I've done something very similar with what looks like an identical peg bag (although mine is the posh Brabantia-branded version ).
I used three straps - one round the bar, one round the headtube and one round the stem. It's rock solid and big enough to fit my stove and cooking kit or food for a whole day.