Monoprice customer here too. Shipping to Canada can get a bit high, so I try to order as many thing as possible in the same package. The nice thing about them is that the prices are so good that I tend to find lots of things that I want. Often more than one. A DVI to VGA converter? Only $3? Aw, heck, let's buy 4! 😀
One reason the stores can get you is they know you're excited about getting your new TV home and you expect instant gratification. They'll warn you that you NEED a new cable to enjoy HDTV on your set. And who wants to take home a shiny new TV and then have to wait another week for the cables to arrive?
The solution, of course, is to order the cables BEFORE you buy your TV 😀 Then when the salesperson says "You're going to need to buy this $100 cable" you can say "no thanks, I already have one, and I only paid $5" 😀