There have been leaks around pricing of the Nexus One -- screenshots from the site where you will purchase the phone appears that it's going to retail for $529 US unlocked, or $179 US with a plan through T-Mobile.
If you're outside the US though, that $529 turns into ($529 * your exchange rate) plus some pretty crazy taxes and duties if you want to even get it into your country.
Since a plan through T-Mobile isn't an option for international customers, you have no choice but to pay through the nose. Here's is what it will likely cost you extra to get a Nexus One into these countries:
Australia - $103 Austria - $168 Brazil - $209 Canada - $82 Czech Republic - $199 Estonia - $190 Finland - $160 France - $156 Germany - $152 Hungary - $192 India - $106 Italy - $148 Japan - $72 Mexico - $115 Netherlands - $150 New Zealand - $150 Northern Ireland - $123 Norway - $184 Poland - $196 Singapore - $154 South Africa - $185 Spain - $142 Sweden - $218 Switzerland - $104 Taiwan - $70 United Kingdom - $132