Start at the speakers......

I tried that once. It cost me $250 in blown speakers.

Also, I don't believe in buying things twice. Since I'm completely redoing my audio system, I'm working my way from the head unit down. Purchasing an inexpensive amp, and then purchasing a good one a few months later (+ the hassle of storing/selling the now 'old' amp) seems silly. I've seen what mediocre amps can do to speakers. I'm not going that route again.

I can't quite accept the "it's all about the speakers" argument.
Analogy: you somehow put Pirelli Asimmetrico tires on a Dodge Neon. Sure, the car will handle a LITTLE better, but not much. The tires potential is essentially wasted on that car.

Another: "garbage in garbage out." If your amp produces distortion so will your speakers. If the amp produces enough distortion it ends up costing you a new set of speakers.

Rather than saying the speakers are always the first, best upgrade, perhaps it would be better to say, "find the weakest link in the chain, upgrade that."