Agree (handheld AR with Unity, won't need killer hardware either just you cell phone+your PC is fine). But be aware that if you ever want to ship something Vuforia is kind of costly. For quick prototyping Unity+Vuforia is pretty great. ARToolkit is decent but the tracking isn't as good (imo) and there's more hands on with extracting features from the markers yourself etc. Eagerly awaiting v6 which has been "coming soon" for quite some time now. You can also search for OpenCV tutorials, iirc there's a Unity plugin.

If anyone has recommendations for a more open stack I'm listening (own a Unity license but think it's meh-ish for AR). Most certainly would like to migrate from Vuforia since I don't want to bet on something that could just go Mataio and be gone (+licensing cost is pretty prohibitive but acceptable for my use case).