You should have a price DB that is linked to product (and maybe to user too). This way, you can have unlimited pricing by products. This could also be use for conditionnal (for example, the price can be for 9 or less, another one for 10-20 and another one for more than 20 items)
Yes a third DB. I don’t know what is you process exactly to create price, but according to what I understand, price DB should have 3 fields: price (number), user (user DB) and products (products DB)
So when user go to product page, you have the pricing using Do a search for price where user = current user and product = current page product