Too mnay factors, you cannot just base your price on Pr. # of outbounds links Relevant page Number of word on page etc.. Are all factors to consider.
You really can't base it on that either, the idea is to just go all out and start building links, so in other words don't be one of them people that set around and pick at links all day because if you do that you won't ever have rankings. Links are Links, just get relevant links.