As far as I know there is no reason why not as long as what you are selling is 'as described' and the quantity (weight) is as listed on the label. i.e. if someone thinks they are getting 500g of Jam it must be 500g not 475g
They will of course need to be cleansed and sterilised in accordance with Food hygiene regulations.
I just wonder if there could possibly be issues with lids that were not specifically made for those jars not sealing correctly?