As they say "Give a man a fish and he will eat for a day, teach a man to fish and he will eat for the rest of his life."
So instead of giving you a link I will try to explain how to narrow your search.
ATmega168 comes in 4 different packages (see the datasheet), so you need to specify which one you want. I assume you need the through-hole (DIP) package, so select this in the package box.
You will get a few results, most of them are out of stocks versions. The two stocked versions are two different frequencies (10MHz or 20MHz). Just get the 20MHz, it's the same price.
Hope this helps.