He was sitting in a parked car in the Main Street area of the town around 10.45am with money in his hand when the thief jumped into the vehicle, snatched the cash and ran away.
The robber is believed to have been carrying two boxes of electric razors and is described as being approximately 20 years old, of slim build, with short hair. He spoke with a Republic of Ireland accent and was wearing a grey body warmer.
Police later received a report that a man and a younger male were trying to sell electric razors, jewellery and watches to passers-by in Main Street.
Anyone with any information about this incident is asked to contact Lisnaskea Police Station on 0845 600 8000. Or if someone would prefer to provide information without giving their details, they can contact the independent charity Crimestoppers and speak to them anonymously on 0800 555 111.