Hello Mark,
I think that nearly all selenium toners on the market are based on the same base formulation: Sodiumselenite (about 2 g) + sodiumsulfite (about 15 g) + ammoniumthiosulfate (about 27 g) dissolved in water (56 ml) like KRST. Maybe the ratio of the substances and their concentration vary a little bit and the dilution is a little bit different.
I think the older versions of elementary red selenium dissolved in a sodiumsulfide solution or red selenium dissolved in a sodiumsulfite solution are no longer on the market.
If you have access to chemicals please remember that sodiumselenite (Na2SeO3) is very very toxic, especially when inhaled!!