I had the same question on my first Camino last year and ended up getting a “Demo Bags” from Amazon.
I wanted something that was:
Large (45” tall, 30” wide, 42 gallon volume)
Inexpensive - $2.50/bag
Strong – (100 lb load, for broken glass, brick, cinder block on construction sites)
Tear Resistant – woven polypropylene (similar to the Ikea bag but stronger)
Light – less than a pair of socks
Small Volume when not using – size of a burrito from Chipotle
Reusable – worked great Round trip from USA last year - 8 flights where the bag was handled (3x - switching planes, 5x - baggage claim pick up)
Unique – so no one accidentally took my bag mistaking it for their own.
No straps - to snag on baggage handling equipment and then get ripped open
I bought a few reusable zip ties from the hardware store to cinch the bag closed near the top. At the check in counter, pull out the Demo Bag from your pack, insert pack into Demo Bag, put zip tie on loose for looping around the identifier tag or adhesive strip the airline attaches to a checked bag and then cinch it tight. As soon as I picked up my bag off the luggage conveyor, I dragged it away from the crowds, removed the zip tie, pulled the pack out, folded up the bag and put it in the pack thus negating the need for straps/handles. The bag sat at the bottom of my pack for the whole Camino. Because of all the attributes above, it was ready to be used again when I started my travels back to the USA eliminating the time and cost of finding/buying a new travel bag before leaving Santiago.
Downside to the Demolition Bag:
It’s not stylish
Minimum purchase size is 5 bags for $12.99 (for a life time of Caminos)
Except for the straps and the smaller size, the Ikea bag looks good. I’m always suspect of zipper quality and thus consider it just one more potential failure point. My pack was big and would not fit in the Ikea bag…be sure to look up dimensions and capacities of that bag before purchasing it. I do think most Camino type back packs will fit in it. I just looked it up, these are the Ikea specifications: (L- 28 ¾” , D-13 ¾", H- 11 ¾", Max. load: 55 lb, Volume: 20 gallon)
Demo Bags – on amazon
https://www.amazon.com/dp/B073H9RQQH/?tag=casaivar02-20