tournament pay scales

I've searched everywhere and cannot find a formula to create a tournament pay scale. I have seen the end result of scales created, but I would like to make my own. Can you help?

I have a feeling there are about as many pay scales as there are tournaments, or at least tournament organizers.

Of course, the first two questions that need to be answered are, what is the total prize pool, and how many places pay out? If the second answer is a percentage, then it gets harder as you can't really calculate anything until you know how many players there are.

Here's a suggestion, although I have no idea how well this plays out in real life (I just looked at some of the payouts of the minor events at the WSOP and got a general idea):
The winner gets 1/3 of the total prize pool
Each place below the winner gets 2/3 of the place above it, although you can group some places together and divide those places' payouts equally among them.
Whatever is left over, is added to the winner's prize

Example: if the prize pool is $1000:
$333 to the winner (actually, $366 - see below)
$222 for second
$148 for third
$98 for fourth
$65 for fifth
$43 for sixth
(if you want fifth and sixth to pay equally, both get (65 + 43) / 2 = 54)
$28 for seventh
$18 for eighth
$12 for ninth
This is $967; the remaining $33 is added to the winner's prize, making it $366

I appreciate your input, but I was looking for a mathematical formula that would calculate a payout spreadsheet.