Well I'm a developer with enough technical knowledge and I'm willing to work in a start up. maybe we can have a chat about ?
Another option is to search on the freelance/upwork websites as well on here. The main prerequisite should be the work commitment of the developer(s), as people have mentioned expensively priced developers doesnt necessarily guarantee satisfaction or commitment.
Don't worry too much on the pricing, instead think more of the quality terms. As the prize increase so will it be with the quality. If u want to have your apps built within a short span of time, I would suggest you to choose Agriya who are well-versed in developing clones of most of the popular apps within your desired budgets.