With Black Friday and Cyber Monday right around the corner, you can expect to see some hot deals in the upcoming weeks. This makes November the perfect time to buy a new smartphone like the Galaxy S5 or Note 3. In fact, T-Mobile recently announced plans to sell both of these devices at $100 off their original price. But there are a few things you should know before you head out the door to your local T-Mobile store. The deal will begin on November 21, at which point customers who purchase either the Galaxy S5 or Note 3 will notice a $100 discount automatically deducted from the total price. This isn’t a standard mail-in rebate like many companies offer, but instead it’s an automatic, on-the-spot deduction. T-Mobile has the discount programmed into its computer system, so anytime a customer buys one of the devices he or she will see a $100 discount taken off the price. So, how much will the Galaxy S5 cost with the $100 discount taken into account? Unfortunately, we’re not quite sure on the total price, as T-Mobile failed to answer this in its announcement. The current sale price for the Galaxy S5 is $609.60 down,…