If you look at AliExpress, I found some good trace mix there & they have potassium phosphate & urea, though no potassium nitrate. That is, if you have access to AliExpress. It is much more user friendly than AliBaba itself is.
Unfortunately, potassium nitrate can potentially be used to make explosives so it tends to be a bit difficult to find. I can get it here (Canada) but only in one place I know of & one must upload a copy of one’s drivers licence before they’ll sell it to you in strictly limited amounts.