An updated price comes in to a cell each minute "googlefinance()". In a second cell we start with a reference price which is typed in manually. The initial value is equal to the first price that comes in on the price feed.
As time goes on, if the a new updated price varies from the reference price by more or less than 0.5%; We want to replace the reference price cell with the most recent updated price and then add the most recent updated price to a new cell in a column that records all of the changes to the reference price.
Is it possible to do this with a custom spreadsheet function?