If you have canti brake bosses the cheap tiny front sun lite rack that was everywhere a few years ago makes a great way to carry a camera bag as a front bag. It is just big enough for a camera bag. They were available for about $12. They are less common now, but you can find one on ebay for under $10. I prefer it to a handlebar mount even for my bag that was designed as a handlebar bag. I didn't bother to attach the bag super securely. I just set the bag on the rack and used the shoulder strap to keep it in place. It was quick and easy to grab the bag and take it with me.