Re: Expense, reliability and support
I'd check your actual state DMV site for legality of the bike. Michigan requires the same deal, but in all actuality it really depends on your neighborhood po-po. 9 out of 10 of the police in my area (the county sheriffs) actually dig the bike I ride. If you're going the 49cc route there really isn't too noticeable speed than a regular bike as stock 49cc's generally max out around 25mph. I ride a Micargi Falcon GTS with a Grubee 49cc and most times unless you're going with the throttle wide open you can't even tell it's motorized if you're riding in a car. When the po-po is around, kill the engine and pedal if you're worried. Just don't be dumb about it. Obey the street signs (bikers here tend to run stop signs and lights) and use hand signals. Pay attention to people getting out of their cars so you don't get hit by a stray car door.
If you're going for a 80(66)cc engine it's a whole different story. I've gotten a bike yanked so far b/c they can cruise. If you go for one of those, you'll definitely 100% want a second brake besides the coaster and remember to drive the speed limit or inconspicuously so the fuzz doesn't nab you. Even on the 49cc's you gotta remember that if that manual pedal chain derails or breaks, you are flying without any brakes whatsoever. the Schwinn Jaguar that you can find at Target for just over $100 has front and rear caliper brakes and is a solid bike.
And yes. get a horn. I mounted a 110db electric boat horn on mine because people in cars are generally idiots hellbent on doing everything they can besides paying attention to the road.