The only inexpensive battery banks are lead-acid, and lighter weight means lower capacity and/or won't last as long.
You should install your bank in place and never need to pick it up and carry it around.
If you can spend 7-10 times more, lithium can save weight but will not have the same capacity, still too heavy to easily cart around without a dolly.
The first step is to make a list of the devices you plan to power, along with a guess of how many hours per day.