Rod,be careful of cheap e-bay product,you need to establish the life left in the battery and the cost of a replacement. Bosch replacement batteries cost £450 upwards,some cheap secondhand e-bikes can have nil value,if the replacement cost of the battery is more than the value of the rest of the bike.
Nobody suggested that you should spend £3-4k,such sales at this value tend to be a second or third generation buyer. But for what you want a £1000 budget may be more realistic.
KudosDave