I carry enough cards to never need deleting during the trip.
I copy the photos of each day to a laptop and to a portable hard drive.
This leaves me with 3 copies of each picture.
The laptop has lightroom though I rarely use it during the trip. I can open and view RAW images without it.
My setup does not meet your under $500 criteria but as most u/w photogs discover, nothing in this endeavor fits a reasonable budget.