Nutes and medium are kinda funky to buy on Amazon. I’ve found them cheaper to buy locally on multiple occasions.
I prefer to buy this stuff locally regardless of price though. Your local hydro shop can be an excellent resource, and bail you out in a pinch too. Having a lot of them should keep them fairly competitive. I would visit one or two and poke around some. Ask questions, see if they seem knowledgeable and helpful, or at least a place you don’t mind spending your cash. If you find someone that seems knowledgable, ask them what they recommend and why. Then verify they carry all or most of the product line, and go with your gut from here.
Any of the nutrient lines can supply your needs. I would maybe question if they tried shoving you right to advanced nutrients. They’re good, but you need a butt load of bottles to follow recommended schedule and its expensive.
You’ll need base nutes, can be 2,3, or 4 part depending on brand. You’ll probably want some calmag too. And ph adjusters of course. You can probably get by from there. You’ll have plenty of time to investigate any or which flower boosters you many want, so no need to worry about those now. Things like silica, root stimulators, microbial supplements, and sweeteners all have their place but are usually not required.
The recent movement seems to be going toward dry powdered nutrients for synthetics. Very Similar to 2 or 3 part, just not yet diluted in water. You can check these out, usually a little cheaper.