It is super easy to make, and will cost you about $5 in materials each. I wasn't referring you to the site to buy one - sorry. It was the picture. That site is linked to my What Is A Sump page on my own site.
If your bulkhead is 1", you'll want a reducer (1.25" to 1" -or- 1.5" to 1"). If the bulkhead is threaded internally, the reducer needs to have threads. If it is a slip fitting, the reducer should be slip.
Then all you need is the same size (1.25" or 1.5") tee, 90 degree elbow, and cap, plus a length of the same diameter pipe.
No glue necessary, just press it together. Drill a 3/16" hole in the cap.
My reef has two of them, and it works perfectly and silently.
If you prefer to make covers to avoid snails or fish going down the drain, some have secured eggcrate (lighting diffuser) over or within the elbow's opening with zipties.