It honestly depends what "reasonably priced" means to you. EcoFlow has some great battery options. I find my ResMed AirSense 11 used about 40% of the capacity of an EcoFlow Delta 2 (1024 kWh capacity) using 110V AC. That was with humidification and a heated tube over an 8 hour night.
You could probably get one of their high-end River models and a 110W panel to recharge through the day.
Using a DC power cable for the CPAP machine may save on some conversion. So it would go DC from the battery to DC for the CPAP instead of DC from the battery to AC 110V back down to DC for the CPAP.