Jeez, I was lucky to have two functioning nav/com radios when I got my IFR ticket.
terrykrummrey, Marc Z is spot on. I would not rely on any GPS based equipment as a flight instrument standby system. The only comment I will make is to wait until the last possible moment to buy your avionics because the market is quite fluid. I know of a protracted build that has two Blue Mountain EFIS units in it, ever heard of them? Marc Z probably even knows who I'm talking about.