Base price as cost price
My biggest client use the base price as it is meant to be used - for the price that pay to their own supplier, i.e. their cost price.
Then they add different profit margins for their various shopper groups to get the selling price and than apply tax.
That is all they want to show, price to their customer and Tax.
No way do they want their cost price to be shown.
Base price as basic price
For another client who has a flexible profit margin their selling price is shown as Salesprice without tax (i.e. their basic price).
Which is obtained/calculated by entering the selling (final) price at which they want to sell the product and working backwards, deducting tax.
They then show that base (for them) price, the tax amount and the final price.
They do check the calculated base price just to ensure that it is more than their actual cost price.
Nothing tricky about these two at all.
I don't think my clients ever want to display their cost price as it discloses their profit margin!