Are you talking about horn tips to turn? If so, I have contacted 6 different people in the last week or so and no one has any tips to sell. I find it hard to buy tips sight unseen unless they come from another Horner, as they know what you need.
If you find a source please share it with us.
To help stop delaminating I find drilling and rough turning the stock as soon as possible after receipt. One batch had the ends painted to slow or stop the delamination but still had voids in them,
Good Luck, Tim