First, $2500 covers 50 hours of work. Do you think your app can be written in that timeframe ? Hardly. So this amount is not a compensation, it's more of a marginally attractive retainer.
Second, the 10% share is a joke. The reason being is that if there is a written app, then 10% commission gets you a simple e-com distribution (shopping cart, invoicing, payment processing). The 30% commission buys you a "fire and forget" kind of deal - you give the distributor an app, they brand it, promote, market and sell it and they also provide front-line support. THIRTY PERCENT.
You effectively offered a guy a 90% commission deal and now seem to be surprised he isn't happy. I wonder why.