Complex IF Statement

I am trying to do a complex IF Statement and I cannot figure it out. What I am trying to do is if the IF Statement result is FALSE I want the entire formula to delete so, that I am able to type in that cell. If it is TRUE I want it to calculate a formula. Here is an example of what I what I am trying to do:

I am creating an estimating spreadsheet and I would like the estimators to pick how they want to come up with the GM & Price. I want them to either enter in the GM they would like to receive and then a unit price will automatically calculate or I would like them to be able to enter in the unit price and then the GM automatically calculates.

See example below:
My cost per unit is $200 (cell A1), I want the option to enter a GM (cell A2)of 25% and my unit price (cell A3) automatically calculates to $250 OR I want to be able to enter a unit price in cell A3 and the GM (cell A2) automatically calculates.
Would this be an IF Statement? Is this going to be a circular reference problem?

All help is appreciated!!

You would have to use code to do what you are looking to do. Please see my reply in this thread.
http://www.excelforum.com/excel-misc...-in-excel.html

Why don't you just put a message like "enter data here..." if the result is false? The cell wouldn't be empty, but that doesn't really matter.