isblank to ignore formula

Dear Forum.

Wondering if someone can give me some guidance on how to achieve the following? Please see attached file which is a theoritical sample of what I'm trying to accomplish.

There are two 'Examples' in the attached worksheet (example 1 and 2). They are basically the same thing except that in example 1 the 'Price' input cell (C5) is looking at another cell (i.e. contains a formula) for it's value (looks to cell K5). In example 2 the value is to be input by the user.
For example 1 the answer is returned in cell D15, which has the same formula structure as the answer cell (D32) in example 2.

So, example 2 is producing the effect that I want, i.e. unless each of the 5 inputs (cells C22, C24, C26, C28 and C30) have values then the answer (cell C32) returns "Missing Info".

I want to be able to do the equivalent for example 1, i.e. that unless there is inputs in cells C5, C7, C9, C11 and C13 that it would return the answer in Cell D15 as "Missing Info". However, because in example 1, cell C5 contains a formula, the answer (cell D15) returns "0" rather than "Missing Info".

Is there a way to overcome this so that cell D15 would return "Missing Info" rather than 0 prior to the input of all the cells?

Any insight would be appreciated.