How 2 offer discount for multi orders of same prod

[Steve McNamara]

Hi all:

I sell a CD-ROM, and I'd like to make it easy for buyers
to pay full price for the first CD, then purchase addl CDs
for a lower, flat fee.

For example:

Qty 1 = $130
but only $20 more per addl, so:

Qty 2 = $150

Qty 3 = $170

Etc

Any ideas how to do this?

Thanks,

Steve