I read thru half of this thread and then I started to tear my hair out. Which is hard, since I'm bald.

I think it would be a great exercise to find the most boring, cheap, disposable and yet functional items to put together in a BOB. That way you'll have it and not agonize over it or cannibalize it.

Knife? Cold Steel Bushman and a CRKT M16 folder.
Multitool? Go to sogknives and see if they have a seconds Pocket Power Plier.
Hydration pack? Get an Eagle Creek pack and stick a Platypus bladder in it.
Stove and pot? Get a tin cup from Campmor and make a wood gas stove from a coffee can.
http://www.garlington.biz/Ray/WoodGasStove/
Hell, get another coffee can and use that for the cup.
Flashlight: Mini-mag.
Towel/Water Filter/Filter Mask/Bandage: dish towel.
Radio: Transistor Radio, ten bucks.
Clothing: Carhartt pants, Red Ledge Thunderlight Waterproof/Breathable Parka, Old Navy or Gap Fleece shirt or maybe an old wool sweater, 2 t-shirts, 2 pair skivvies, 2 pair socks, 1 pair Sealskinz socks, beanie, boonie hat. Resole those old work boots. Gardening gloves. Add your least favorite pair of sunglasses.
Tent? NOPE. Bivy? Hefty bags and duct tape.
Food? Clif Bars, and grab that salami from the fridge.
Maps: Auto Club. Silva Compass.
Crowbar from hardware store. Spark-lite, or cannibalize your Zippo. Cheap cigar lighter. Tea Candles. Whistle. 550 cord. Safety wire. Fish hooks.

First aid kits are easy to buy. Get Bull Frog spray and Chap Stick too.

A paperback copy of Watership Down and a deck of cards.

Documents? Keep your passport in there. Take it out when you travel, put it back when you return. Data backup? Use your iPod.

The initial layer of clothing should be kept in a hefty bag that's taped to the backpack. If you have time, change. If not, grab and run, when you get to an interim spot rip the bag off and change.

The whole thing can be kept in a Rubbermaid tub under the bed along with a bottle of water that you rotate with the one in the fridge.

Is it that difficult?