Summary
We are start up and we provide software development services. We develop windows, web, services and mobile applications. We were aware of agile and we are scrum certified developers . We do user story based estimation and task planning. No issues.
Issue
We are approached by many small customers. Customers says very high level features or few words about the concept of their dream project. They asks for Effort Estimation and Cost Estimation. Mostly they are interested in Cost.
For each customer we did create the user stories and estimated the user stories and based on story points, we estimated the effort in days and we convert the days to the cost based on hourly rate. We involve the team of 3 or 4 people and get the estimation done. We spend at least 20 to 30 hours of team total time for estimation. (Team of 4 discussing for 5-6 hours)
The problem is that many customers would never turn back. We do not want to spend 20-30 hours of team effort. We don't want to use the exact user story estimation that we follow for contract signed project.
Question
What could be done in order to provide approximate estimate for small customers with small business?