I'm not sure what your use-case is here, but LEGO Education is probably the most expensive way to simply buy parts. When you purchase from LEGO Education, you are also paying for access to a bundled classroom curriculum in addition to the parts you are buying. In essence, these shouldn't be valued in $/part, but something more like $/hour of learning experience.
If you are looking to design your own learning experiences, or you just want a pile of bricks for students to engage with, LEGO Education is likely not the best value. In this case I'd recommend buying regular sets that roughly match the part profile you are hoping for. If you are comfortable buying used parts, then I'd recommend sites like Bricklink, BrickOwl, or eBay.
This related question may also be of interest:
What's the most cost effective way to buy bulk LEGO bricks?