Figured it out, just a bad translation from c#
UIDClass needs to be UID
'Get dockable window.
Dim dockWinID As UID = New UID()
dockWinID.Value = "ArcGISCostEstimatingTools_ArcGISProjectCostEstimatingWindow"
Dim dockWindow As DockableWindow
dockWindow = My.ArcMap.DockableWindowManager.GetDockableWindow(dockWinID)
dockWindow.Show(True)