Stop Idoc creation on conditon

Gurus,

I've a situation where I get a message from third party system, that message will be creating Idoc in SAP. I wanted to get Idocs created only on condition basis. If cost of material is greater than 50, then only create Idoc otherwise don't create, I don't even want to get the Idoc errored out if condition is not met. Message type and Idoc type are standard.

Please help me.

Regards

Raj.