Your question is related to asking why is the same exact fabric sold online in a very big popular store for one price, and our local quilt shops sell it for up to $4 more per yard.
Why does a seller online in a popular site charge $6 to ship one yard of fabric, but another seller will ship free or up to 9 yards for the same cost?
Overhead with middle men, employee pay and benefits, utilities, insurance, shipping, loss prevention, etc. etc.
What does a DVD cost? Roughly $1 to make, add the production costs, employees, etc. etc. and then warehousing, processing, employees, etc of the middleman, and the profits at retailers to pay out these same types of expenses, and the customer pays from $9.95-$33 and up for that $1 initial cost.
Thankfully our local LQS has monthly bag day and at least one fantastic sale a year to bring fabric down to @50% off. I can't go overseas to shop so I will gladly pay what my favorite shops ask for.