B&Q and other outlets sell a small bag for £4.99, but you can claim yours for free (although I do try to take out most of the stones, please do not think I have time to sieve it all, some bagged. So swap some of your rubble sacks for mine, or leave your bags for me to fill, although this may take time). You would need to hump the sacks from the back to your transport around the front (ideally with a sack barrow) and clear away any mess you make, which is only fair.