You definitely need their special abacus, it is central to the teaching. A normal one won't do. You could make your own, we did just for fun, but it won't be as solid as the one they sell.
The card game set is nice and I recommend making sure you get them, although I've never used the DVD and only browsed through the manuals. So far all the games have been described in the manual.
Most people would have some of the other manipulatives at home that they can use. I ended up buying the whole kit, as I didn't have the geared clock, the abacus cards, the place value cards, and the scale. We use the place value cards and geared clock a lot.
