The technology advanced again a little bit. The well-known glassmaker and -blower Rinaldo substituted certain components in old recipes with others, cutting the price to a half, without loss of quality. Great business!
The party will be hired by a merchant or a glassmaker, though a Guildmaster may be their real employer. They shall find out why Rinaldo suddenly lowered his prices and still seems to make a nice profit. Does he want to start a business war, or has he perhaps changed the original recipes, handed down from generation to generation? Heaven forbid!
After many sighs for all the bad business upcoming, they are instructed to find out exactly what is done and why it is done and to keep it all private.
The sounder minds may recognize several problems:
1) There IS something unethical about this.
2) This could be well against the laws (there may not be laws for exactly this crime, but its definitely against all guild laws and rules, which are but seldom known to public).
3) This is really industrial espionage.
If the party already has some dubious reputation, they would be instructed to ‘delay’ him for a few weeks or months (sabotage the process, once they found the secret and hand it to their employer). Otherwise, the roguish character may be approached individually, with a little bonus for some extra work…