Well, topic name is pretty self-explanatory… Quite disappointing, since it is the only way to earn money early on (just when you reach Helios City)…
Rushing the story until you get to Sonata City might work. Tho you could go Rock Smashing in Helios Sewers (Meloetta Puzzle cave) and sell the Soft Sands and Hard Stones and also get IV Stones and Heart Scales along the way.