Block Sales Order if Line Item Value is Zero

Hello,

We have Quantity Based Scale Pricing (e.g. if for a given Line Item in Sales Order if the Line Item Quantity is below 100 ,the Line Item Net value becomes Zero ).

How can we Block Sales Order ,if due to Qty Scales ,Price of any Line Item becomes Zero.

We have one option of using  sale order User exit in the program MV45AFZZ - USEREXIT_PRICING_PREPARE_TKOMK to achieve this requirement.

Is there any other better Option/Standard Option to achieve this .......

Thanks,

Vikas