What would you do ?
Don't watch black & white....
This is a pickle, especially with the warranty expiring so soon - AND the fact that it is an aftermarket (non-Panasonic) warranty.
Our 60ST30 was eventually replaced for a Growing Pink Tint (by Panasonic), with a 60ST50: But that was in April of 2012, and the ST30 was still under Pan's warranty.
FWIW, the local service representative was NOT impressed with Pink (or Green) Tinting that appeared on BLACK & WHITE programming.
However, the Pink Tint on that last ST30 finally reached the point where it was Clearly Visible on COLOR broadcasts - and that seemed to be the rationale behind finally replacing the set.
Hard to imagine that they would be able to find any "new" ST30 panels (let along full tvs!) just sitting around. And it would likely have a similar problem in any case (although Pink / Green tints DID vary from set to set!).
IF the PQ remains good on COLOR broadcasts, you might have to live with it, although if it were MINE, and someone offered a Reconditioned ST50, would jump at the swap.....
Best of Luck!