I'm looking at the Games Workshop site because I'm thinking about what side I'd play as. I think that the Imperial Guard fit my preferred tactics very well, but to get Assault on Black Reach, a Cadian Battleforce, an Imperial Guard Cadian Command Squad, an Imperial Guard Chimera, a Imperial Guard Leman Russ Battle Tank and an Imperial Guard Codex costs a total of $477 Australian. If I leave out the tank and the command squad, it's still $367. If I switch Assault on Black Reach with the rulebook, it's $348. I'd be willing to pay either of those last two. Anyone got any advice or recommendations for me, keeping in mind that this is all theoretical and I'm not about to go out and buy anything?
You don't need the Assault on Black Reach package at all. That's an introductory box with a stripped down rulebook, some scenery bits, and piecemeal set of Space Marine and Ork figures. If you want to start a Guard army from scratch, just buy the Guard stuff.
Your list of stuff to buy is a little odd to me. A Battleforce set plus a Command Squad actually isn't enough units for a basic army - you'll need more infantry. Trust me, the best way to start is to get the Codex, then decide how you want to build an army, before buying any figures.