If you search eBay for pocketwatches under $4, you can find a huge variety for really cheap. I buy them for $2-$3 each (free shipping) and use them to make necklaces, but a pocketwatch can be worn on a necklace chain or as a keychain and there are a ton of styles, ranging from vintage-looking to skulls or footballs or trains. The downside is most of the cheap ones with free shipping have to be mailed from Asia, so it takes a few weeks to get to the US. If you don't mind paying slightly more you can find US resellers with shorter shipping times, if that matters.