Yeah, cheap is relative. Depends on if the project is a daily basher or a 1/8 nitro bug.
The triangle still has relevance though to me as one tool in the thought process of initially brain-storming a project. But you're correct on nothing being cheap anymore. Time was when I kept a spreadsheet on expenses. Not anymore. I don't want to know.
I understand budget builds. After you've spent your first grand you take a moment to assess what else you might need. The RC snowball effect will have its way in the end.
As an automotive technician, I frequently use the same triangle. If somebody is in a hurry, it won't be cheap. If your in a hurry and broke, it won't last long.