I did some online research on what parts would be the most cost effective.

It seems that it could be significantly easier and cheaper to find a Motorola Lapdock and hack that, rather than get a separate battery, LVDS LCD display, VGA to LDVS driver board, HDMI to VGA converter, 3D printed case, etc......

In fact, I think it will be MUCH cheaper and easier to use a lapdock. I think now I should aim for under $100, not $150. However, I could still use a 3D-printed case/shell to attach the RPi securely to the bottom of the lapdock so no cables are exposed and so that everything is all in one streamlined unit that can be slid into a backpack without catching on things and ripping itself apart.

Since I'll be changing the list of parts, here's the current list for future reference:

• 1×Raspberry Pi 2 Model B - adafruit$40 + S&H
• 1×full size (11-12") keyboard with touchpad - amazon$25 shipped; hack to move touchpad below keyboard from the side
• 1×USB wifi stick - amazon$10 shipped
• 1×Acuvar Power Bank 13000mAh Dual-Port Portable Charger With LED Battery Life Indicator - amazon$15 shipped
• 1×4GB microSD card - class 10, with SD card adapter - amazon$6 shipped
• 1×13" LVDS LCD - ebay and MT6820-B LVDS driver board - ebayabout $30 + S&H and $10 shipped
• 1×active HDMI to VGA adapter - amazon or otherabout $10 shipped
• 1×powered USB 2 hub - dealextreme$6 shipped
• 1×3D printed caseabout $10 of filament??
• 1×screws & hinges + misc. wire, hot glue, solder + S&Habout $10 including adafruit + ebay S&H

lol, I started out looking at 6V 1.4 ah batteries that are $8 each... but that would be so heavy. and they are .95" thick