Tank dividers are sooo expensive to buy! Just DIY! I didn't have anyyyyy of the materials (nup, no silicone glue either) before but I still saved money making a divider myself.
$3.99 - Silicone glue (the 1oz I got should be wayyyyy enough) [Petsmart/lfs/hardware store/art store]
$0.74 - Plastic craft sheet (the mesh divider) [Walmart]
$2.19ish - A package of sliding report cover (Avery's 6 pack; that means you can make 2 more dividers with this) [Office Max]
Total: ~$7.
From what I've seen, tank dividers are usually $12+. Once you have these materials, to make more dividers, you just need to buy more plastic craft sheets (which are either $0.25 or $0.74 at Walmart, depending on what size you want) and you already have the other material! Tada, money saving. I'm all for saving costs where I can.
I used black sliding report cover bars and my tank looks pretty snazzy (whether I have the mesh divider actually in or not). B)