I thought I could use a powered usb hub, connect the 6 cameras to it, connect the hub to the raspberry pi and capture the images one after the other quickly using the motion package. But I can't find cheap, tiny (hopefully under 20 x 20 x 30mm) usb cameras with at least 3 mega pixel resolution. Is it a good idea to open a few usb webcams and see if they fit my size requirements?
If I can't find small, cheap, good usb cameras, I'll try using CMOS sensors, but I can't find out how to actually use more than one camera sensor with a development board. I'll appreciate any pointers on that. For example, how can I go about using six of these cameras - https://www.sparkfun.com/products/8667 - on one board?
The actual project is to take multiple pictures covering 360 degrees and upload them to a web server. All cameras will have to fit in as small an enclosure as possible (budget is $300 including the development board). I apologize if these are real noob questions - I'm new to electronics and have only done basic projects on raspberrypi and arduino till now.