Scenario
You would like to have a list of specific items only available to order for some customers.
Solution
1. Create an Item Saved search by going to Reports > New Search > click Item link
2. Click created Saved search
3. On the Criteria tab > Standard add the following filter:
>If only one item, add Name and select the specific item
>If multiple items, add Formula (Numeric) is equal to Value is 1
>Formula = Case when {name}='XXXX' OR {name}='XXXX' OR {name}='XXXX' then 1 else 0 end
Note: XXXX represents your Item name. You can add more items and just copy "OR {name}="XXXX"
4. On the Results tab, you can just add Name and Display name
This is the result of the Item saved search.
5. Create new Sales Order, and on the upper right portion click "Customize Form".
6. On the Sublist fields > Item Filter > select the Item saved search
7. Save
As a result, using the Custom Sales order form. You can see the list of Items you added in your saved search criteria.