A 3$/month server can serve hacker news traffic fine (~100 realtime visitors). They usually sell with unlimited bandwidth..
more like ~250 online visitors at any one time from what I have seen
It probably depends on timezone. Friends posting here told me it's no use to post anything when US are asleep.
(edit : and btw, I've noted myself it's no use to post comments when I wake up from France, since it's already old news for US and they are asleep as well ;) )