http://www.evuk.co.uk/news/index5.html#Low_Cost_Lithium_Ebikes_in_UK
It is good that you are interested in alternative transport, but your question is rather cyptic -
where are you, what are your needs? how far, what loads, how often, how much money? etc.
make your own, school project, full sales & support package?
please try again with extra info & you might get better answers