Shalom
We're very glad you'll be visiting Israel again, especially on our 60th Independence Day!
You'll discover that the country has changed tremendously since your previous visit 30 years ago. Nowadays you can get in Israel everything there is in America and at comparable prices. There isn't really something the Israelis miss and cannot purchase in Israel.
Therefore, your question is more a matter of the personal taste of your friends. If you don't know of anything specific they need, you might want to look for a more personal gift.
Best regards and looking forwards to seeing you in Israel!