I agree that if ivory became so devalued, the poaching would cease. The only problem with that, is a ban won't accomplish that. Just for the sake of the argument, lets say a ban in the USA dropped world wide demand by 50% (which of course it wouldn't, IMO it'd be more like 2%) - There would still be enough value for the poaching to continue. Even if ivory was banned in every country, there's still enough demand to continue the poaching, in my opinion.
This is where we differ. Poaching really isn't high risk for the locals. There's hardly any enforcement, and the elephants are literally in their back yard. How long do you think it would take someone to shoot an elephant, walk 100 yds, cut the ivory off and be gone? 10 minutes? I'm sure there are some poachers that don't even go looking. They just go on with their life, and when they see one, they take it. It's entirely too easy, and that is the sad truth.
Whaling is a bad example because of the time and risk involved. Going out and finding a whale, killing it, and than having to haul it back to a local port where there's always traffic is very risky. Not to mention the pure size of it is much harder to conceal than a couple of 5 ft long tusks, especially when your hut is only a stones throw away.