Required website and Android application development projects on commission basis

I need some help with my business. I am looking for some website amd android applications development projects for my startup..On commission basis. A percentage amount will be given from the total amount of the project. Looking for long term relationship not short term, so short term ones please don't connect. As the customer payed in milestones, so the percentage amount will be also paid in milestones who bring the project. We don't pay upfront payment. As we receive money from the client after a part of the project is delivered then only we will pay the commission or else not. For Big project big commission will be given.