(Please ignore this nonsense, I don't know what I'm talking about)
Well looking at this from a logical pov, the 128 gb one is $20 which means that you're paying roughly 16 cents per gb, but for the 356 gb you're paying $30 which is about 12 cents per gb, so it'd be better to buy the 356 gb if you're buying in bulk but if this is just a one-time thing and you don't have money to blow then it'd make sense to go with the cheaper option
Also, buying two of the 128 gb chips would equal one 356 gb chip, but you'd be paying $40 for the two chips instead of just $30 so you'd be paying $10 extra (but again, this would be a good deal if you really wanted all of that space. if you don't think you're going to use all of it then yeah, buy the 128 gb chip).