Trekster – yes, you're right in your assumptions.
The 'USB' bit refers to the name of the 'plug' that the memory connects to. Sort of modern day PC equivalent of a 3-pin plug.
The 'flash' part is the actual memory on the card.
You can get them for pennies especially if you only need a small capacity one, but it's worth spending a couple more pennies for a decent brand. It's not unknown for them to got kapput which can be annoying if you're now sitting at home trying to get to the work you've brought home (ironically on a USB memory stick with a logo of you own compny on – cheapskates!).