From you description this is what you got today:
download bmml source – Wireframes created with Balsamiq Mockups
This is perfect to drag and drop, and it has a nice direct feeling of control to the user. A 150 products is hard to organize in one category, and I think you need to categorize the products. Having the categories as filters, the user can within a category order the products in the first iteration.
When this is done in all the categories of product, users could order all the products in a second iteration to get the complete list of products in order. This implies that there is no order between products in categories.
If there is order between categories, then the user could simply order categories first, and then products within categories.