I did not buy any fm to standby. However, gynae clinic did provide sample. I just kept that as standby. I am 100% sure I want and will bf hence the brand of standby fm did not matter to me.. After all it's just for a few feedings.
Yes, I did had to supplement few feeds in the beginning, but after that already fully bf so fm is thrown out. Personal opinion but I feel that no point pondering too much over which brand milk if you are determined to bf. Any brand, small tin is good enough for standby.