Man, Dave i wish I could remember where I saw some one having those in bulk. They were the black ones like Estes used for the last Sterling kits. I searched eBay but found nothing. Maybe contact Estes and see if they have stock remaining? They sell rockets kit parts in bulk so if they have them on hand they may be receptive to selling some.
Do you need any handles? I have accumulated a lot of the Cox RTF handles over the years. let me know , send me an email I can send photo to and I'll send you some pictures.
Type at you later,
Dan McEntee