Product Size & Price

I am trying to achieve this by dropdown menu

Spice 10g - $7.00
Spice 25g - $13.50
Spice 50g - $25.00

I was trying to do it by creating an attribute but it is not changing the pricing correctly.  I am getting $7 and then when selecting Spice 25g the pricing changes to $12 and it does not adjust.

Can I just have one product with 3 sizes and it will change it to the designated price instead of add/subtract from main price?

Thanks in advance for any advice.

Maybe Group Product would work better for you.

I achieved this using product attributes and left the product price at $0.00.

Thanks,