Do I find out the hard way after I make my purchase with the educated guess that Bitcoin pricing is stable long enough that from my understanding the more popular Bitcoin is worth and the more money each Bitcoin is worth among other factors is what influences the Bitcoin Fee is there an app of some sort I can use on my Cell Phone to let me know the current Blockchain Wallet Sending Fees will be as that is the Wallet I am using for simply Sending Bitcoin into and Sending out of. 


  Any help explaining how this works would be greatly appreciated as it is frustrating not knowing what my Bitcoin Fee is going to be hence I don't know how much money in Bitcoin more than what I am spending on my purchase that I need to acquire?