There's an incentive through some of the association membership benefits such as NAPP or ASMP, a student or teacher, etc.
Generally, you get about 15% discount off the software and if you purchase/upgrade to Photoshop CS-5, you can purchase LR for about $100.
If you are a member, another benefit of your membership. If not a member of a group, sometimes this will pay for that membership and give you lots of other goodies as part of the process!