In this paper, traditional capital budgeting models (or the models for investment appraisal) are extended and some new models are developed for realistic representations of financial decision making by firms in the conditions for common and interdependent projects, termination of projects when these are significant set up costs for new projects, conditions for sustainability of the business when some projects may collapse, and constraints on borrowing. Theses extended models can be applied for undertaking real life investment appraisal exercises. This paper, therefore, makes a valuable contribution to the literature on investment appraisal in accounting, economics and finance.