As mentioned in the section about organizing a SAM team, migrations are a key part of the software asset management discipline.
Deciding which products to displace, what the alternatives are, selling the users in your shop, managing the migration, and playing the migration card in negotiations are all important issues. A listing of some of the alternatives is the only part addressed here. Remember, not everyone uses a software product in the same manner. Alternative products will have some functional overlap, but may not satisfy all your needs. Examine the missing functions carefully. Are they really needed? Are they worth the additional cost? Is there another way to accomplish the same result? Are their additional functions in the replacement product that are more valuable to you than the functions you would be losing from the existing product?
Over time, some suppliers improve the functionality of their products. You may discover that enhancements in another product you already have may be sufficient to allow you to simply cancel the license for a product rather than replacing it. At other times, a "do it yourself" little program might work if you are only using a limited subset of a product's function.
IBM offers alternatives to many ISV products. A partial listing is available at
http://www.ibm.com/software/solutions/softwaremigration