Recent few experiences -
- I bought a 60usd keyboard from epomaker and they themselves undervalued it to 20usd without me asking or anything, it was shipped via yanwen and customs were handled by morning global - Zero customs were levied.
- Ordered a 15usd item from alibaba, these guys also undervalued it to 5usd on their own. It was shipped via china post and cutsoms were handled by India post - again Zero customs were levied.
- Ordered a 50usd watch from a spanish website, they undervalued it to 20usd. It was shipped via postNL and customs were handled by india post which also did the last mile delivery - 1200rs custom duty levied.
I think if the parcel is small and really low valued then chances of getting custom duty levied are very low if handled by india post.
Try for shipping method where customs is handled by morninglobal or similar vendors, most likely no customs then.