Don’t know of any variety (error or otherwise) from that year. They do have a lower mintage than your typical circulated penny and show at $.85 each in MS65 in this year’s red book. If they aren’t taking up too much space, you might as well hold onto them as long as you can stand. A quick look of completed listings on ebay shows them going for about $6 a roll currently.
Pennies were 95% copper, 5% zinc in 1973. Copper skyrocketed that year, doubling in price from fifty cents a pound to a dollar a pound. So, those pennies contain more copper than current pennies, I suspect. There was mich discussion at that time regarding what sort of change needed to be made, to make pennies economical once more.
You might want to check value on mint uncirculated 1973 Lincoln pennies again, too. I’ve seen fifteen to thirty-five cents cited as a value, for example:
http://cointrackers.com/coins/13669/1973-lincoln-penny/