I have dressed up as a witch (for work). Found a black dress at the thrift store and embellished with halloween stuff; old broom or stick with a colored ball glued on top; pointed hat (not too difficult to make) and you are good to go. My friend always goes as a Hershey candy kiss!!
Raggedy Ann and/or Andy are good for work costumes as well (smile). Dorothy from Wizard of Oz also good. Please show pic of what you come up with. The thrift stores are the greatest of places for these types of fun items (smile).