" I am a rich guy looking to buy a weapon. Instead of paying for it at a higher price from a dealer, I quit my job and make the weapon for minimum price and then once I have the gun I quit guns dealer and rejoin my original job"
This could be an issue and you may need to have it so people cant join the guns dealer job for at least 3 hours of gameplay since quitting another job. I am not sure if thats the best solution but maybe you could go off that. Thanks for your time.