I think on balance it's more hassle than it's worth
That depends where you place the term hassle and worth?
Building your first sump and make it work flawlesly can indeed be a bit of a hassle. Especialy for the people overthinking and overcomplicating the sumps design with unecessary bells and wissles.. It doesn't make it a beter filter. A sump can be (should be) equaly KISS and fool proof as is a canister.
Sumps are mainly build by people with large tanks.. Over 2 years ago i took the challange to build a small one from a 25 litre standard eurobraced aquarium from the LFS. Cost €15
Used €15, 4mm acrylic sheet material. (Actualy only half of the sheet i bought)
Pump is not a fixed piece of hardware, you choose what to place in it.
a €29.95 pump
And a €20 PVC materials to create a proper drain system.
It hold over 5 litre Biomedia and some sponge material, nothing fancy.. But volume wise it could easily filter an aquarium up to 500 litre.
Total sum
+/- €80,- for the complete setup. Didn't add the media because a cannister contains about the same. But in case add a €20 extra.
Try to buy a completely ready to run canister for a 500 litre tank for around €100. I guess you have to search a very long time to find it..
Actualy this sump runs a 110 litre tank at the moment.. And i couldn't find a cheaper canister for that either. That's worth something
But honnestly i must say as a first time DIY project not realy knowing what i was into. It took me a while, some experimenting and hassle to realise that Keep It Simple Stupid is the best way to go. Once you know/realise that, every sump build there after is a laugh.
That's worth something as well..