Custom price formula for updateprices

[Rudd-O]

Let's say you have a currency called "Gold Sovereigns". This obviously cannot be looked up in Yahoo! Finance. But, would it be so bad to have an option to set a custom formula for the price retrieval of that currency, such that the formula would read something like "XAUUSD + $30", and so updateprices can eagerly compute the equivalent price in USD at the same time it retrieves the XAUUSD price?

Seems like a nice feature to me. That way, things that perpetually float above or below a certain currency (that can be looked up) can get price quotes.