220
Cheap and They Don't Snitch: Drones Are the New Drug Mules
(www.vice.com)
This is a most excellent place for technology news and articles.
They're not that loud though. Unless they're really close you'd probably just ignore them unless you knew to be looking for it. Especially if you're flying deliberately and not just randomly taking turns or stopping.
They make tools for drones that let you remotely control extra addons attached to them. In particular something that can remotely drop a payload could let you fly by essentially unnoticed easily.