How can I filter Craft Commerce products by the current price
https://craftcommerce.com/docs/variant-model#saleprice

The comment on the documentation leads me to believe you can just use salePrice for your filtering as it will be equal to the defaultPrice if there is no sale.

So:

{% set queryParams = {
        relatedTo: category,
        salePrice: [
            'and',
            '&gt;= ' ~ 0,
            '&lt;= ' ~ 90,
        ]
    }
%}