If your current phone's battery is the only issue, consider a $89 battery swap instead of a $800+ new phone.
This is the worst time to buy. You are paying full price for a phone that will be "old" and cheaper in just a few weeks.
If you want a cheaper, smaller phone, Apple often refreshes the SE line in March or April.
By spring, the "Apple Certified Refurbished" store usually has plenty of the previous year's models at a steep discount. When to Wait