“and want to buy stuff tomorrow”
…Don’t. I believe that Soylent is safe if it’s done right, but right now it’s very experimental, and everyone has to find their own ideal mix.
Everyone has to make sure they don’t overdose on some vitamins and nutrients, which can be very very easy and very very bad.
When I first heard of soylent I wanted to immediately have it too, but actually following through on that urge it’s quite possible you would end up killing yourself.
You should check out the different spreadsheets you can find scattered accross these forums, inform yourself a bit about recommended intakes etc, and then make your own spreadsheet, detailing your suppliers and the exact products you are going to use, with all their ingredients etc.
When it comes to actually buying stuff in physical stores, you’ll probably end up visiting health stores, fitness stores, a chemist and a supermarket.