Effective 1 February 2013, Autodesk will simplify its upgrade pricing model. Starting next month, all upgrades will cost 70% of the current price for a new license.
The “Upgrade from Previous Releases” option will have an Autodesk SRP of approximately seventy percent (70%) of the current new License Autodesk SRP*, regardless of which of the six previous releases is being upgraded. Autodesk product releases more than six releases prior to the current release will no longer be eligible for upgrade.
For Softimage, I imagine the “six previous releases” covers only the Autodesk releases: 2012, 2011, 2010, 7.5, and maybe 7.01. I doubt it will cover 6.5, but you should check with your reseller to make sure.