Re: complete newbie to motored bicycles
Welcome to the forum, Ben.
This place is a wealth of information, and what DuctTapeGoat said is %100 correct. I would personally build myself, just for the pleasure and cost effectiveness. But, a great way to go is also the already made method. I could almost even send you towards an E-bike. They're pretty efficient, but nothing can replace the vibration and noise of an internal combustion engine.
Either way, read what people are saying in this forum, and listen to them. I had a BLAST putting my bike together, modding it, and now, it's even a bit more fun riding it, knowing I built it myself.
Have fun, and be safe