We like this Marc by Marc Jacobs safety pin barrette  (pictured) but the $32 price tag isn't in line with our "save for vacation fund" plan. If you're feeling crafty, why not do it yourself?
To bond metal to metal, soldering is an option if you know what you're doing, but perhaps not the most practical. The easiest — and cheapest — way to go about it is to affix a large safety pin to a wire barrette backing (found at most craft supply stores) using Krazy Glue  ($3). Clamp to set, and then go make some for friends, do "The Safety (pin) Dance," and revel in your cash-saving brilliance.