The turn by turn one day price is extremely misleading.

Just looking on my device for European maps:

1 day = €1.70 per day (higher price probably due to our local sales tax)

30 days = €7.65 = 25.5 cents per day

365 days = €59.95 = 16 .4 cents per day

...and the other services are free anyway so if you can manage without turn-by-turn then you pay nothing.

Also, I suspect the N900 will come bundled with a period of free turn-by-turn anyway. Most mid to high end Nokia smartphones come with a free Ovi Maps subscription (i.e. turn-by-turn) of either 6 months, 1 year or (on navigation-oriented bundles) lifetime.

EDIT: People can use the trial subscription to see if it works for them, which is probably the best policy as the quality of navigation software seems to vary quite a lot depending on where in the world you live or travel.