What's a simple, cheap treatment for my clavicle fracture?

Clavicle fracture. In most people with healthy bones clavicle fractures heal very well on their own. The best thing you can do to help is to use an immobilizer. The classic over-the-counter immobilizer is a figure-8 strap to hold the shoulders back and keep pressure off the clavicle during healing. This is available at any pharmacy. Other styles of immobilizers are also available.
Sling. A sling is the best nonoperative treatment for a clavicle fracture; figure of 8 braces have been shown to be less tolerated by patients and have no short or long-term advantage. They can be cumbersome and painful to put on correctly. A sling should be adjusted to fit correctly - it should support your elbow without forcing your arm/shoulder upward.