Both scenarios are absolutely true. I guess the question you gotta ask yourself:
Do ya feel lucky? Well, do ya?
You're taking a gamble by waiting. You could lose out on what you really want at a reasonable discount, or you could miss out on a better deal. Flip a coin.
What he said.

In our experience, when someone wished to purchase a demo/display unit, we asked for full payment upfront and then he/she can come by on the last day to take it away.
If there is more than 1 buyer then we shipped it to the next person in line after the show.