You seem to have missed the fact that this is a
service. It's a SAAS targeted at businesses. The economics have little to do with iphone apps and desktop software. And complexity of software has no relation whatsoever to its utility.
Running a service is expensive. First you have customer acquisition, which is not magical and free as you seem to believe, then you have servers to run, email services to pay, security updates, new features, server admin, customer support .. unless you are running at an amazing scale you just cannot do that for $10/year.
> would you rather sell one hundred subscription at $120 per year or ten thousands subscription at $10 per year
Where on earth are you getting these numbers from? You don't automatically get 100x the sales if you drop the price. This is just pure fantasy IMO. More likely he is going to get 100 sales either way, because he might manage to get his product in front of 100 people for whom the problem solving value exceeds the cost, and who has a $10/yr problem?
Fact is this a product targeted at businesses. The type of people who are actually interested in paying money for someone to solve their problem do not care about the difference between $10 and $100. Do you save them $101 worth of time? Then sold! If anything I would be suspicious of a low price like $10/yr because I know it's not viable.