In price vs performance my list goes
Home made Wet/dry
Emperor 400/Aquaclear HOB filters
Canisters
Of those, a wet/dry is by far the best.
Here's all I needed to get my 75 gallon wet/dry running
HOB overflow (
Here's an e-bay auction for the one I use.)
67 liter storage bin from walmart (15 bucks)
3 drawer steralite shelving walmat (12 bucks)
PVC for plumbing. (straigth pipe, dozen elbows, two unions, and 2 ball valves)
A pump. (Quiet-One and Mag-Drive are recommended by some folks here.)
I'd say shoot for 6-900GPH. You will need a pump that puts out more then 6-900gph, due to head loss, but check the pumps curve to see what you'll get at about 5' of head.
Bio media. Pot scrubbers (Nylon) from a dollar store are 1 buck for 6, can't get any cheaper. They also are more effective then the over priced bio-balls you get from fish stores.
I'd also recommend getting some mechanical filtration. Filter floss (polyester pillow stuffing
NON FIRE RETARDANT is the same stuff, and can be found at any place with a craft section.
I'll have a picture coming.