Cai's crop-delivery quests are a documented way to turn farming activity into gold, with Faerghast reporting rewards of 2,500 gold for the harvest requests shown in his guide. These are quest payouts rather than evidence of an unlimited gold loop. If you want money for an immediate purchase, check the available request and your stock before spending exploration time on a supposed infinite method.
Turn Cai's harvests into quest income
Faerghast's crop farming walkthrough describes a sequence of harvest-delivery quests after agriculture becomes available. He explains that each of the requests shown asks for a combined total of thirty crops drawn from its specified plant group, and reports 2,500 gold plus 200 Renown as the reward. Use the active quest's own requested items, rather than assuming any thirty crops satisfy every delivery.
The useful connection is between a field you can grow and a request you can actually complete. Game8's agriculture guide explains that farming begins in Chapter 6 of Cai's Path and requires owning the crop you plant. That makes the method conditional on route progress, the relevant quest and suitable crop stock, rather than something every protagonist can immediately perform.
Read later delivery rewards individually
RPG Site's Part III walkthrough provides another concrete example of quest income. Its Arena Construction Effort entry lists delivering three Building Materials for 3,000 gold, 100 Relief Points and access to training. That is a specific later-story request, so it should not be presented as an endlessly repeatable exchange or an early-game farming route.
Use the story progress guide to distinguish a request available now from one in a later part. Check the required materials against their other uses before delivering them simply for cash. A quest's gold reward can be helpful without making it the best choice for every inventory or current objective.
Separate earning money from reducing costs
If the immediate problem is an expensive purchase, a discount may reduce the gold you need. Game8's Boon guide lists weapon and item discounts, while other Boons target different spending categories. These reduce expenditure rather than generate gold, so compare the intended purchase with the applicable discount before treating them as a substitute currency farm.
For the crop requests above, follow the actual quest reward and stop when its delivery is complete. Neither guide establishes a repeatable hourly yield, an automatic quest reset or an unlimited sale loop. Keep the Renown guide nearby if the same delivery serves both your cash needs and the reputation objective you are pursuing.