The majority of consultants and developers bill by the hour. At Instead of following other consultancy firms, we decided to give our clients the possibility to pay for each project.
Why? Because the focus will be on deliverables and not what it took to get there. Also, the price is according to value, not time. The client will know exactly how much a project will cost, thus mitigating the risk of budget overflow with time-based billing.
Besides the above, it just makes sense. When you are going to buy a television, you will pay for the product and not the amount of time it took to build the television.