In the five years since the iPhone came out, there has been a
gold rush to develop apps, but a new report shows just how hard
this business can be.  Vision Mobile, a market analysis and
strategy firm, surveyed more than 1,500 developers worldwide and
found that one in three apps generates $500 or less a month,
which means developers have to find other sources of income to
get by.  On average, developers make between $1,200-$3,900 per
app each month, though some platforms prove more lucrative than
others. For example, iOS developers surveyed make more per app
each month on average ($3,693)  than Android developers
($2,735), but both fall short of what Blackberry developers earn
per app each month ($3,853).  Those are just some of the big
findings from Vision Mobile's report on the state of the app
economy in 2012.