If you have a Kinect sitting around from your XBox 360 like I did then you might be pretty close to decent quality 3D scanning.
Get the software
I use Skanect but there are open source alternatives. You can use Skanect for free but you will have a 5000 polygon limit. The full version is only $129 which isn’t much for what it does.
Get a power supply
These cost less than $20 and allow you to connect your Kinect to a PC or Mac and power it through a wall outlet. Simply Google or search on Amazon for “USB AC Adapter Power Supply Xbox 360 Kinect”.