I was going to say the same thing; this actually works really well. "But Amazon does it!" becomes a less compelling argument to people when they see how much they'd have to spend to be like Amazon.

Nah, this doesn't work. Clients think you're just lying and trying to take advantage of them.

If you have a client asking for million dollar features on a 100k budget, the only solution is to find new clients. Some people are beyond help.

This is why building trust by starting small and delivering exactly what you said you would for exactly the price you said is key.

Clients and stakeholders alike will never cease the asking for more than you can reasonably deliver because they have absolutely no way of knowing how reasonable their request is. That is why pulling all nighters and heroics are so bad for developer / business relationships. They set a precedent for what is reasonable or possible.

If the client or stakeholder never really can have the data necessary to fairly judge whether you are "holding out" or not then the only thing you can do is build personal trust by doing what you say you will, not a damn thing more, not a damn thing less.

I generally do if they press the point, or some similar variation. "Oh, but Google does XYZ". And again, yes, but... their budget has 3 extra zeroes on it. etc...