I'd like to have a backup just in case I need one. Any suggestions what company is the best to buy one from?
Thanks in advance....
There're quite a few of choices actually.
If you have a higher budget for this, take a try New trent.
It's inbetween $70-100.
If you have a lower budget, RavPower is a great option.
Theirs is compatible with many devices and brands.
So make a choice yourself.