More then likely a code they gave at one of those con gatherings. Special to those that can afford to hit the events in certain cities 
http://wiki.cohtitan.com/wiki/PPD_Hardsuit_Costume
OR
http://wiki.cohtitan.com/wiki/PPD_Ha..._Costume_(PAX)
...I forgot what experience means.
Note: You can also be rewarded this costume (or the Freakshow Boss or the Carnival Harlequin) for participating in events now and again.
There have been forum costume contests, radio contests and other such events that have given these kind of rewards.
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BTW, has anyone ever noticed that the PPD Hardsuit costume is actually not the PPD Hardsuit worn by the PPD, but is instead the PPD Shell?
Well, that would explain it.
I logged on in RWZ in the AE building and saw a MM there with the exact setup as this Costume I tried PM'n him but he never responded back. It was in the justice server, his name was "Locks". Did I just briefly see a gm/dev or is this an actual costume piece you can unlock?