It all depends on how valuable your time is. It's kind of like linux.

Yes, you can piece something together and save a few bucks, but if you have to come back and redo it later, well, you didn't really save anything and wasted quite a bit of time and effort.
That's especially true with the pumps. Some folks on other boards brag about the "deal" they got on a ShurFlo pump on eBay, then a few months later, they're bragging about the next deal they got to replace the $49 pump that just burnt out on them. Yeah, you got
quite a deal on that noisy pump that's in the garbage!
That was money well spent, wasn't it?
Although, I have met quite a few folks including a local dart frog lady because of these "great deals".
I now have a One Cage Special that includes everything you need for one cage except for a reservoir (pump, nozzle, screen cage adapter, timer, tubing, etc.).