Lots of battery backup sump pump systems at Home Depot. Most of them include a new pump. I don’t know how powerful your current one is. You could get a complete 1/2 HP system for under $500 easily.
https://www.homedepot.com/b/Plumbing-Water-Pumps-Sump-Pump-Backup-Batteries/N-5yc1vZbqp7
Not everyone cares about this, but for those who do, these will most certainly say "Made in China".
To get a high quality pump made in the US or somewhere else in the civilized world, start at your local plumbing supply house.
This is a situation where you do get what you pay for, in my experience.
Those are the ones you see most when you Google. Since I already have a sump pump with a float, how do they work? Do they have a float? If power goes out, do you turn it on so it will clear the pit? Thanks for any insights.