All my tanks use plastic canvas and the spines for booklets, easy to do and I just buy tubes of Everbuild AquaMate, always have a tube or two to hand for emergencies cause of the number of tanks I have.
Plastic canvas can be bought from Hobbycraft and the plastic spines (which I sand first to provide extra grip before glueing them into the tank) come from Office World or even Staples office suppliers. The Aquamate I get from a builders merchants I know who buy them in for me.
It's a lot cheaper to buy and fit your own dividers (make them specific for your tanks) than to buy the pre-made stuff which are rubbish to fit.