Its just business.
MSRP.
Retail stores buy in bulk and get wholesale pricing.
The maufacturer prefers large wholesale orders over single retail sales.
The manufacturer encourages retail buyers to visit retailers...who buy in bulk, but they'll take your money too...at full MSRP.
Its a common business practice.
This way they dont compete with their wholesale clients.
Thats why they a are huge company, and most modders are small time shops.