I am trying to find my thread on this, as this weekend I am buying a few vape related things(RDA, Subtank mini, and flavour concentrates). The best place was mama somethings juices in wales, I'm pretty sure If you google mama's vape wales it will come up. They had all sorts of concentrates, and they are cheap! A few pounds each, and a litre of PG is about £5, same as VG, so you can make your own juice for pennies
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