buy a 40-50 gallon tank for the sump and a pump to push the water flow you want
use a 5 gallon bucket or some office divider shelve at walmart and make your own wet/dry filter
you can combine them into one or make one for each overflow.
pipe the system with PVC
(very easy and cheap to do!!)
I spent $100 on the one i made for my 75 gallon
that or build algae scrubbers in the sump. very effective and no need for skimmers from what i'm reading all over the web