It depends on the country too.

In Brazil for example (not that I have any hope of the N900 being here any soon), most people will buy a smartphone like this on contract, especially because the data plans that make a phone like this worth it will almost always be on contract. Mine for example is R$ 69,90 / month for a 1gb quota at 600kbps, and believe me, that`s kinda cheap for Brazil, and you don`t get to pay what I pay out of contract.

(Today`s exchange rate: US$ 1,0 = R$ 1,88)

Just for comparison terms, the cheapest iphone you can get here is around R$ 550 (this is BRL, not US$), but only on a plan that will set you back around R$ 350 a month. Most expensive Iphone (out of contract) will lighten up your wallet at around R$ 1,800 to R$ 2,400.

Yeap, we get it bad here =(