Microsoft FAST Search Server 2010 License with Software Assurance through the Microsoft Open Business Program.
IMPORTANT NOTE:  A minimum of 5 licenses is required

Microsoft FAST Search Server 2010 for SharePoint combines a market leading enterprise search platform, plus the best of SharePoint with the simplicity and low TCO that customers have come to expect from Microsoft. The result is no-compromise enterprise search that provides a powerful user experience, that is highly capable and easy to manage, and gives customers the power to tackle the most demanding search requirements.

Open licensing is for small to mid-sized organizations that have less than 250 desktop PCs and who order as few as five licenses.  Benefits of Open License include, discounts off the retail price of software, the ability to track and manage licenses by using online tools, and the rights to create a standard image and deploy it on multiple machines, and rights to transfer licenses from one machine to another.