Calculating total fees based on different fee brackets (for eBay fees)

Here is what I am trying to calculate. The following are fees for whatever a given total purchase comes to... so it is basically totalPurchase minus the following... this is a free calculator I am trying to build.

7.0% of the initial $50.00, plus 5.0% of the next $50.01–$1,000.00, plus 2.0% of the remaining balance ($1,000.01–total cost to buyer)

This is how I have done it but the middle equation is what I think I have wrong.

=((C8-1000.01)*0.02)+((C8-50)*0.05)+(50*0.07)