The easiest way to kick the single-use plastic bag habit: a packable tote you can have on you all the time. This collapsible tote is water-resistant, stain-resistant, and made from recycled plastic bottles. Includes a handy carabiner loop so you can clip it to your bag or stash it away.
One more useful thing made from the off cuts of Ticket To The Moon hammocks to avoid waste in our factory, the keyring bag weighs in at a tiny 40g and hangs on a stainless ring. It folds to fit anywhere, so you have no reason not to carry at least one with you at all times!
Market bag of 20 litres capacity with extreme endurance and made of materials that have long lifetime. Easy to use and reliable, not only for shopping but for every other circumstance.