In order to ensure accurate cost calculations, you must keep in mind company size and also understand the intricacies of the various ERP pricing plans. There are two primary models: Perpetual licensing and Software as a Service (SaaS). Simply put, a Perpetual license will allow you to use the licensed ERP system indefinitely. It allows a company to host the software on their own servers and provides a well-defined initial cost of ownership. SaaS subscription pricing is an increasingly popular choice for small businesses. It provides the system on an on-demand basis without lengthy contracts or large upfront costs. The cost of the subscription is typically linked to the number of users accessing the system or the volume of business transactions. Each model offers advantages and disadvantages depending on the size of your enterprise, the scalability required, the number of locations and the complexity of your operations. An experienced  ERP consultant is the best to guide you through the selection process.