Okay you can check bulkreefsupply you can get 7lb of calcium chlorite at 17.9$. You get the same thing with sodium carbonate at the same price, you total 36$. As per randy farley holmes recipe 500g of powder to make a gallon. You get 7lbs / 500g: about 6.2 gallons of liquid solution part A and B.
Depending on your bio load and stock, if you have high demand sps and mix reef, you might be dosing 1ml/gal a day each part equaly 5 mins apart that's. In my case i have a 100g tank with refugium included so i dose 100ml a day. With 6.2 gal i have 23.450ml thats like 234 days of dosing which is 7,8 months.
Now i am not sure how much you dose and how big are the kent bottles you bought. My guess they are at 500ml. With the above schedule i wil only get a month of kent dosing if not couple weeks.
All the above info i took it from randy's article, more more details check "improved diy 2 part" at reefkeeping website.
I have a younger mainly sps 120g tank and I am using about 120mls a day for both alk and calcium. Using the brs is very cost effective, and using dosing pumps, the values stay very constant in my tank. I get about 1 month per gallon of each solution, which amounts to maybe 6 to 7 dollars per month.