Ah, I think you may be in error there....Yes, I think there will be some higher costs for derailleur maintenance for those riders who use high power mode, and especially in hilly areas. However, none of the current bikes use 10 speed and 9 speed is a rarity, most e-bikes use up to 8 speed derailleurs.
.
What about:
Kalkhoff Pro Connect S10 DL
...which will only set you back £3365.00 from 50 cycles!
Rog.