China called, they want their wall back. In all seriousness though you can still buy them from the guild store and shard shop (talking about the salvage, not the implant).
Also keep in mind that this game has always been about prioritizing characters/factions that you want to work on. Just because you have 28 toons that currently need a fully crafted mk8 biotech implant doesn't mean you have to put one on each and every one of those characters... Be patient, focus on a few specific characters at a time so you aren't spreading yourself too thin.