at the begining of the week i asked whever Urban Mover Motion Electric Mountain Bike for £799 is worth it but some one said why dont you buy a bike and make a electric bike your self for cheaper. Sorry forget who it was. I have been thinking all week and decided i would try and build one my self. But where would i start. I live in the UK so i would buy the stuff i need from the UK like the batteries and bike but where do i start. so is there any decent uk web sites where you can buy spare parts to make you own electric bike.

Thanks for any advice.

Edit
I will be using my normal old mountain bike at first to practice on then i will proly buy a newer bike if i can do this.