Can I sell colocasia leaves (patra/arbi leaves) separately for extra income?

Yes, in regions where patra (steamed rolled colocasia leaves) and similar dishes are popular, the broad tender leaves of non-acrid varieties have a real seasonal market, which can add income on top of the corms. The key is to grow a low-acridity variety, because acrid leaves itch and will not sell, and to harvest young, tender, undamaged leaves. Treat leaf income as supplementary and seasonal rather than a guaranteed earner, since demand peaks around certain festivals and regions. Selling both corms and leaves from the same crop improves overall returns. Confirm which variety gives good eating leaves and the local leaf demand with your KVK and nearby vegetable market.