The trouble is that if you set a price that is very nearly free then you are inevitably competing with actually really free. Dan Ariely's research has shown that customers massively overvalue anything free. Customers overwhelmingly prefer a free good to a good at any price, even when there is a significant difference in quality. No experimenter thus far has managed to break this natural gravity towards free in preference to any price. Add in the inevitable friction of the act of payment and you've got an overwhelming barrier to entry that without fail drives the mass of the market towards free alternatives.
There have been a litany of failed micropayment services, all of whom failed for the same reason - rather than doing the Agile thing and finding out what the customer wanted, they tried to impose a 'great idea' on a market that has consistently rejected it. Why exactly are you going to succeed where dozens have failed? What are you going to do differently?
http://www.predictablyirrational.com/pdfs/zerofree.pdf http://www.shirky.com/writings/fame_vs_fortune.html