Make sure you have all sound packs and you should get upgrade pricing if you are up-to-date with all instruments except for Lounge Lizard and Multiphonics.
Similar story. In fact I already had lots of UVI and really liked their stuff, but waited for a great deal on the vintage synth bundle. Then when the Sonic Bundle launched, including all vintage synths, I jumped.
I only have a few favorite devs I got an (almost) everything bundle from: Arturia, EastWest, FabFilter, OrangeTreeSamples and Zynaptiq.