I love cycling but because of an injury I am unable to do it as much as I'd like, my friend let me have a go on his ebike and it was amazing, so I want to put one together myself.

It'll be used mainly for on road (daily commute) but occasional light offroad (gravel, dirt tracks and grass), so MTB would be best. I would like it to have dual power modes, 250w for everyday use and 1000w 'no pedal mode' for occasional use. Would like it to be as light as possible, so carbon fiber frame and other bits but with one eye on durability, especially the moving parts like gears and chain
Also would like to get best bang for buck, I know it'll cost some but if there are any good deals out there I would take that route.

Shopping list
>Frame - Carbon fiber hard tail
>Wheels - Light but durable rims
>Tyres - Decent for road and light offroad, tubeless
>Disk brakes
>Pedals and crank etc (light)
>Group set, chain - focus on durability
>Handlebars, grips, brake levers etc, saddle and stem (lightness and comfort)
>Motor - 1000w with 250w mode - Quality and durability
>Battery and charger - best bang for buck

Plus anything I missed, also any tips and/or advice you may have would be very much appreciated.