Well, I apologize. I mean, if your prices are still:
1-50000 = $1
50001-150000 = .75
150k+ = .5

...then the formula should read:

=SUMPRODUCT(--(A1{0,50000,500000}),A1-{0,50000,500000},{1,-.25,-.25})

Sorry for the error above. The last { } shows the differential as you go
through the tiers.
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