Re: GMing a Post Apocalypse campaign
If you're still going for a Fallout Adaptation I could give you some of my Resources i've been using Failing that Here's what I did the streamline my campaign
Excel sheets (Any similar program will suffice) These make weapon/armor/general equipment managing for purchase, bad guy gear, or simple shopping list for the players a breeze simply hand them the list and tell them what's available at the shop. It's best to make the list of things the players would either frequently buy or things that they SHOULD buy I.E. Gasmasks, stimpacks etc...This will also allow you to know the standard pricing of an item without having to constantly think about it. Simply look at it's average price and modify it to fit the shop owner (I.E. Jerk who over prices things or a indebted shop owner who sells at a discount)
The above listed thing has helped the most for me but another item that's useful is Weapon Tabs these are simple print n cut tabs made specifically for interchangeable firearms, Fallout being a setting where the average player is going to go from POS homemade pistol to somthing better and then something better beyond that it helps to have these items on standby for when the player wants it...Say for instance after they blow away the raider who had a auto shotgun? wouldn't it be nice to go "Oh you want that gun? well here ya go" rather than listing off stats and dragging the game to a halt.
These are just some things that made GMing much easier for me in most games. It takes a bit preparation but it's worth it in the end.