In the way you did it, you're using big PVC with caps designed to hold pressure. Pressure is the whole problem. Most people want to do it with a bucket, or something, which won't have the presure and the problem of sealing holes, etcs. Using PVC the way you did, obviously yours can hold the pressure, and it's driven by an outside pump.
First, great job on doing one the right way and showing it can be done.
With that said, that big caps and PVC pieces aren't cheap, then the pump, tubing, all the quick connects, if you would have added ball valves for the disconnects, etc, then media, you are way over cost on what a better canister filter with media would have cost you, probably by far, but none the less, good job on showing on how to do it right.
Now if you work in plumbing and have all kinds of pieces like this left over after a month of work, then sure, it's a more feasible project for sure. That's a big cost of this project, especially in Canada at least.
20g platy, , 2 x 10g shrimp, 3 x 20g shrimp, 7.5g shrimp and 1 great dane/mastiff puppy.
Sump Pimp #2
My Tanks and my shrimps