This unit cost about 20$ due to using Clear PVC housing, you can use solid 2" pipe if you wish.

You can find all the parts at any Orchard Supply Hardware or Home Depot.

Two: 2" slip to 1/2 threaded bushing
Two: threaded 90 elbow 1/2" barbed
About 10 Bioballs if desired
12" of rigid 3/16" air line
PVC glue
3/16" drill bit
Drill
Powerhead or canister filter etc

This works very well in sump areas also.