eBikeling's initial offerings were relatively small geared kits for about $175. They have increased their product range recently and the latest "3000w" (50+mph) kit is <$600. They also have batteries to 72V, so with the 60 amp controller in the 3K kit, sounds more like 4K+ (forgetting about efficiency since
AFAIK everyone else does too). Too big for me as 33-35 mph is about my limit on an ebike.