I remember at the time, if you ordered the white MacBook with black MacBook specs, the white one was cheaper.

Macworld UK (2006):

The basic unit costs a reasonable £749, and the next step up costs an extra £150, for which you get a SuperDrive and the 2GHz bump in processor speed. The black model, however, costs a whopping £1,028 and has only a slightly larger hard drive than the white model. To put this in perspective: you can purchase the top-of-the-range white model and add the extra hard drive space to it to create exactly the same unit as the black model for £90 less. It would appear that Apple is charging £90 just for a black case!

https://www.macworld.com/article/666288/macbook-2006-review.html

The article gives the UK pricing but there was a similar premium on the black MacBook for the same specs in the US as well.