So, contra the argument that voting is meaningless, it's pretty easy to tell that an individual vote is worth something. And that's because corrupt candidates are willing to pay for them: electoral fraud is very rare these days, but vote buying is one of the most common kinds. The market price of a vote is something like $10-20 ( WaPo). "Everything is worth what its purchaser will pay for it". Twenty bucks is like a typical individual campaign donation, or a couple hours of work. It's not the influence of Sheldon Adelson, but it's not nothing.
For comparison, just over 125 million Americans voted in 2008, which at $20/vote would be $2.5 billion, which sounds about right to me. There was about $2.6 billion spent on political advertising in 2008 all told (NYT)—near on half a billion dollars directly by the Obama and McCain campaigns.
TL/DR: if individual votes didn't matter, nobody would ever pay cash money to get them.