So here is how I altered a handbag to make the perfect handlebar bag.
This is my handbag before modifications.
I cut two pieces of strap, each 7 inches long, and melted the ends with a match so they wouldn't fray. The melting method works great with nylon based webbing.
I now sewed my straps to the front of my bag, about 1 inch in from the side and 1 1/8 inch down from the top. Since I melted the ends, I did not have to fold the webbing under, thus eliminating bulk. The free arm on my sewing machine came in handy here. Remember to check inside the bag before sewing, so as not to sew into a zipper or snap.
I sewed a 2 inch piece of Velcro on each side of the back of the bag and this is what it looks like when the strap is brought over and connected.
So if you need a handlebar bag, look at what used handbags, camera cases or pouches that you have laying around. Why spend $15 or $20 for a run of the mill black handlebar bag when you can have a unique one for pennies. Be creative!