xRM is why it is better to buy, not build
Typically when you buy a product you are getting a boxed solution and as a result you are limited to the functionality of the product within that box. The xRM framework that you gain access to when you buy Microsoft Dynamics CRM allows you to get 80% functionality out of the box while not restricting you to the limitations of traditional CRM products.
With the xRM platform, you are integrating into common desktop applications and allowing yourself to work in a non-proprietary environment. With this tool you can easily create a line of business application relevant to your current needs. Generally to get this amount of customization you have to build your own product, which can be very expensive. Due to the many factors it is very difficult to predict an accurate timeline and come in on budget and schedule.
In addition to this, technology is constantly changing. This requires a lot of time spent updating and managing your custom build, which can be extremely expensive and limits you to developers who are familiar with this custom environment. The xRM framework provided by Microsoft CRM is the answer. In this way, Microsoft allows you to have your cake and eat it by letting Microsoft worry about the underlying technology while letting you concentrate on your business.