It is going to cost you more moeny to make those stds than to buy them What do you have a 4 pH std for ? If it is for seawater all you need is 7 and 10. Even Dr Rand Holmes-Farley does not make is own pH stds.
Yes, there is Craig's old Borax std for ~ pH 9 but that is about all you will find. Take note you have to be able to measure that weight in 1/100 of a gram
I forgot and a weigh scale to 0.01 grams is alike ~ $250