yep or u can get the 50kg one for under $50 and they are perfect for tanks measuring 2 X 1 X 1foot which is $20 each from a tank maker greg in acukand. [PM me for his detail]
one Jebo 9904 air pump [more than enough to run all 3 tanks] $20 and 3 double sponge filter $8 or single for $5 which u can get though barry at fishzone visit the site below for his detail.
http://www.fishzone.co.nz/index.html
u would be looking at no more than $154 for ur basic bare bottom tank
set up. thats the cheapest way i came up with hope it helps