The console can't be as cheap as the handheld.
This has frequently come up in discussions about a potentially low Wii price. Usually the reason given is that it will make the console look too cheap, or that they'd cannibalize each others' sales at a similar price point. I say that history shows this not to be the case. These same arguments came up in late 2003. Game Boy Advance SP cost $99 at the time, and so did GameCube. What happened? By US numbers, both systems had their best holiday season ever. Two cheap systems didn't cannibalize sales; instead they were both successful for the same reason.
2001, November + December
$199 GCN: 1.21 M
$99 GBA: 2.63 M
2002, November + December
$149 GCN: 1.01 M
$99 GBA: 3.34 M
2003, November + December
$99 GCN: 1.91 M
$99 GBASP+original: 3.44 M
2004, November + December
$99 GCN: 1.15 M
$79 GBASP+original: 3.18 M
2005, November + December
$99 GCN: 0.88 M
Micro/SP/GBA: 2.03 M