Check around your local Craigs List, Facebook marketplace etc. and see if you can find what a comparable item is selling for and go from there. Without knowing what shape your bike and it's running gear are in it would be impossible to tell you a price here. Will say that it seems to be a sellers market for eBikes though so you should be able to get a decent price if it is in good condition in all respects and if there is any sort of demand for eBikes in your region.