Back when I used liquid chlorine I found by far cheapest solution was bulk refillable containers. Pool stores here refill for about $8 per 2.5 gal jug for ~10%. If you can find a pool store or an industrial chemical supplier that does this it will be your best bet. Of course best bet of all is install a swg yourself and you won't ever need liquid except for when you open. I waited 5 years to convert. If I had it to do over again I would have switched 5 years ago.