If you're wanting a decent enough filter for cheapest price, check into the SunSun/Prefect line. Talk about them
here. The HW-302 can still be found, $50 for 264 gal/hr. Ebay seller normal list it as a "3 stage canister filter". Amazon has a Aquatop CF-300 that look exactly like the HW-302 but has a different box.
+1 On that.
I have 2 of the SunSun's. They do a superb job for me on my filtration needs.
Currently I have them on a 20 G Long and a 30 Gallon. The flow for the 20 needs to be valved down.
I think that if you get two of thos SunSun for that 55 G, youl find that the filtration capcity will be great and the flow you get will be nearly perfect and you won't go too much over you budget.
You'll still need to get some filter media for thos as they only come with thin medium course floss pads.
All in all I think you be pleased with these -- BTW you don't have to change both media in filters at the same time; you can stagger the changes so as not to disturb the bb and start a mini cycle all over again in your tank.
EDIT: Come to think of it my second was a "Perfecto" --- The two filters look and perform exactly alike and the parts (Tubes) even interchanable.
Hope this helps.
Best wishes,
Wes