Based on a suggestion from a reader, I am including a section on where to buy vests from some of the amazing outfits posted below (see Street Style post). Here are some examples of varying prices. Click each picture for more info.
Lets start with Forever 21, as cheap as it gets (aside from thrift stores, maybe). Paying such a low price for a trendy item is probably a good idea, since you are only likely to wear it for one or two seasons. However, they are not the best quality.
Urban Outfitters is somewhat more expensive, but you really get what you pay for (in a good way!). Here are a few examples.
Finally, try Nordstrom for higher quality designer vests. They are a lot more unique than what you would find at Forever 21 and Urban Outfitters, but also very expensive in comparison!