11-08-2018 11:15 AM
Welcome to our community. You ask a really great question.
Items may be automatically removed from your Cart on BestBuy.com for any of a number of reasons, including but not limited to: price changes, promotional periods changing or ending, or the product becoming unavailable, etc.
Your cart is not intended for long term storage of potential purchases, nor are prices guaranteed to remain the same once an item is placed in your Cart.
I hope this helps. If you have additional questions, please be sure to let me know.