Pretty sure he's already available in the Conquest store, but for crystals. If he's not available for Conquest Currency yet, he will be soon.
Remember, too, that which characters show up is random, so he may be available but you just haven't been offered his shards yet. You can either refresh or just be patient -- you don't need many more shards so you should have him within the week... but I doubt you'll have him before GAC lock-in.