Once again referenced to Spink 2010 (prices in UK pounds, to EUR /0.844, to USD /0.633):
Twopence 1797: F 40 - VF 140 - EF 400 - UNC 1400
Penny 1797 - 10 leaves: F12 - VF 60 - EF 300 - UNC 1000
Penny 1797 - 11 leaves: F15 - VF 75 - EF 350 - UNC 1250
These pieces are quite heavy and often have rim/edge damage from dropping them. Pieces with an intact rim and edge have a better value than those without intact rim/edges.