Effort Estimation with good accuracy helps in managing overall budgeting and planning. The accuracy of these estimates is very less and most difficult to obtain, because no or very little detail about the project is known at the beginning. Due to architectural difference in CBS (Component Based Systems), this estimation becomes more crucial. Component-based development mainly involves the reuse of already developed components. The selection of best quality component is of prime concern for developing an overall quality product. CBS mainly involves two types of efforts: selection and integration. Present paper presents a fuzzy rule based model for estimating the efforts in selecting these Components for developing an application using CBSE approach.