Simples.
Depending upon where you are flying from and how many vendors you visit, the postage alone will equate to a fair chunk of your travel costs . . . . . .
Seriously - even within the UK ten small orders will set you back £35+ in postage.
If you want proper bargains, go hit TTcombat/Trolltrader early on. They have a clearance section awash with various systems and their terrain is nearly always discounted.