Allow me to jump into this tier/user pricing bonfire:

Tier pricing is unfair. This is like my buying a car stereo for my
Volkswagen and being told by the saleman that if I decide one day to put
the stereo in a Mercedes, I owe him more money. The reasoning (?) behind
this would be that, since the Mercedes is much quieter, I gain more
benefit from the stereo. Ridiculous.

Now let's spray some more lighter fluid onto the fire:

User-based pricing isn't fair either. This is like a car dearlership
charging a family of four more for the same car than a couple with no
children. And, advising the couple that, if one day they have a child,
they must stop by the car dealership on the way home from the hospital
to pay extra for the new "user". Ludicrous.

Q. How many elephants can you get in a phone booth?
A. It doesn't matter, the phone call still costs a quarter.

The bottom line (from the customer's viewpiont): what deliverables do I
receive from the software supplier for the money I paid? Here's what I
get:

1 copy of the software to run on
1 machine, with
1 set of manuals, and maybe
1 support contract

Of course, I expect to pay extra for:

Extra copies to run on other machines
Extra Manuals
Increased levels of support

That's all I or anyone else should have to pay for. Ever.
No matter how big the machine is.
No matter how many people use it.

Period.

--Ken Kirby
  Vanderbilt University