luck = chance to find something, not the value.
value of the item you can find is proportional to the amount of labor points you bring to the job.
in other words - equip the best gear for the job, queue the jobs, change to luck gear. for example - you started the job when luck value was at $10.000, and then you change to luck gear and this value drops to $9.000. you still CAN find items valuable more than $9.000.
golden rule - use the gear with most labor points when you queue the job, and gear with bonuses (luck, cash, experience) when you finish the job.