It's a little harder to shop the UK for either single bits, small items or if you need something fast. Sometimes the prices are much better, though shipping often makes up the difference. And, if there's a mistake in the order, then there's getting it back there.
And even the specialty guys (like ol' Anthony's best buddy) make mistakes, and their mistakes become your problems when they shrug and tell you, "I don't know" when they send you the wrong part and you ask them what should you do with it.
So if I'm going to have to eat a mistake, I'd rather it be $5 than $50.
Hey Ed, I can get you one for a tire named "Duke".