I'm gonna stand by the SR4 Anniversary and Runner's Toolkit suggestions, myself. I'm a big fan of "core only" games for folks who are new to any game (but especially if they're new to ALL games)...but Runner's Toolkit is also the perfect second-thing-to-buy, because the OP and his group are exactly the sort of folks it's aimed at. It's designed to help new players and GMs, so it's right up their alley to help out.
I mean, sure. I'm probably supposed to talk people into buying more stuff, especially stuff I wrote, but you know what? I'd rather they travel light, so to speak, learn the ropes, sling some dice, and have fun with the game. If they start slow and simple, learn the basics, and fall in love with Shadowrun, they'll buy more stuff down the line, anyways. If we pressure 'em into buying a ton of stuff they don't need right now, get 'em overwhelmed, and they feel like gaming is work instead of play? We're just gonna be another step closer to killing the game and the hobby, which also is bad business.
So, heck with it. Yeah. Core book, and RT for the hand-outs, flashcards, GM screen, and stuff. Have fun. Tell awesome stories. That's all you need.