Yeah. For bergan sacks you need to go to your local B&Q. Get a Clear gravel bag and some elastic bands. For documents bags Go to aldi and get their food bags. They're sturdy and have a good sticky top for closing.
On a Pte Soldiers wage you have to adapt and overcome. Now i wouldn't go back to being a mug and buying all that kit!
lads i have 2 years to go & have used an IPK for the most of my time to line my bergan.
i am asking purly on behalf of one of my mates as he is off to a trg unit soon & wondered if there was a cheaper alternative to ortlieb as you know what trg units are like. if you were to start pulling naafi bags out of your bergan the grown ups frown upon that sort of thing.