Is it possible to 'force' a price failure in QP?

I have a QP requirement where a price request needs to abort under certain circumstances. Does anyone have a suggestion as to how I might achieve this?

I am building a series of prices from different suppliers for the same product spec (using lumpsum modifiers) where there needs to be a distinction between a price that is zero and a price that is "not applicable".  In the former case, it's valid just not to add any value to the price but in the latter, the whole price request should abort at that point since the supplier is signifying that he does not offer pricing for that element of the product spec.  On no account should just zero be added to the price as that will lead to