From what i've been told, you can have long range, high speed, and low cost-pick two. Not trying to discourage you, but i'm pretty sure that's just how it goes. With my beloved NiMHs locked up by Chevron and the Lithiums being (so far) hideously expensive, most DIY-ers are going with Lead Acid-and that means weight, which affects performance, which locks you into optimum Volt/Amp vs weight, etc. It gets pricey.
Christ, are you rural, suburban or urban? I have yet to produce an EV of any kind yet(need one more test before qualifying for my dream job-and a paycheck!) but when I do i'm going to try a powered Bicycle as my first EV. Since i'm strictly rural an EV Bike will be little more than a Proof of Concept toy, but if you have commutes/errands of under 30 miles a day, a decent Pedal Hybrid, Scooter or small Motorcycle EV could prove both useful and inexpensive. A 1or 2 HP motor would kill on a Powered Bicycle, Controllers are much cheaper-a 3.5 HP Golf Cart motor and a 36-48V controller would make a nice Scooter, etc. Also, any mistakes you make will be less expensive on the small scale, and good practice before the Full-sized conversions.
My own plan will be to make my cheap EV Pedal Hybrid, perhaps make it useful with a Booster Cart(Bike Trailer with extra Batteries in Parallel for more range, plus room for cargo), then later on try my hand at an ultralight, Medium-to-highway speed Trike with 40-50 miles per charge...imagine the Twike and the City-El having a kid, only engineered with Analog controls and Redneck Engineering tech from 1979 or so (gotta stick to what I know!).
Don't worry, i'll announce when i'm ready-give you all time to retreat to the safety of the Blast Shields...
Oh, you mentioned LEDs-those are great for brakes, running lights and turn signals, but check with DOT on the legality for headlights. Some states may or may not pass it on inspection.