>>1621156>was £750?It might be an availability or shipping issue.
There are many approaches to getting into ebiking anon, if you're in a hurry or aren't overly concerned about the overall quality then buying one ready made is probably the best way to go, there are some advantages as mentioned, warranty being one, the fact that the motor and battery are usually integrated into the overall design of the bike, good enough reasons to take that route.
I would recommend you check out some ebike forums
>pedelecs>Endless-sphereThere are others, good sources of info and informed advice, the kind of people who spend their time on such a specifically focused forum are likely to know which ones to avoid etc.
Happy hunting.