I just placed a large order on W9TECH, I purchased the persei, nibbler xl, and SR-74. I added all the items on the persei page and added to cart... I checked without doing the math, and just realized I was over charged. When the persei, nibbler xl, and SR-74 are added as a package it cam out to $515.00, which is what I paid... When the items are added individually the price comes out to $405.00! Please help!