Binary Tree have recently launched the following promotion
http://binarytree.com/Company/News-and-Events/Press-Releases/Binary-Tree-Introduces-Promotional-Pricing-of-$4-P.aspx
Binary Tree Introduces Promotional Pricing of $4 Per Mailbox for E2E Complete Exchange Migration Software at Tech·Ed North America 2011
This is also available in Europe
Contact Binary Tree for more details.