Fixed price or hourly — which is better for me? — answered by Engineer Saeed Baatiah
Fixed price is better when the scope is clear and written down, because it shifts delay risk to the developer and gives you a number to plan against. Hourly is better when the scope is vague or shifting, because a fixed price in that case carries a high risk margin that you pay for. The fairest practical arrangement: a fixed price for a defined first version, then hourly or a monthly block of hours for ongoing development afterwards.