"For the crystal? Fifty credits," Silas said, closing the box. "For the secret of where I get them? That’ll cost you a lot more than money."
Silas didn't look up from his ledger. "You want a lighter, go to the gas station. You want magic, go to the circus." where to buy piezoelectric crystals
If you aren't looking for a sci-fi adventure, here is where you can actually source them: "For the crystal