I look at those strobes kits too, but thought i could find a better use for the money.
Things like snoots are easy enough to make yourself from tubes and velcro and that beauty dish will probably be too small to really give you a proper beauty dish look. The honeycombs are probably of use.
If you're looking for a soft box there are loads out there; the lastolite ones (and the subsequent copies on flea bay) are good... I had a 40x40cm one that was my main location light for working close to the subject. I had one with single diffusion so not masses of power lost and it helped give some really soft light without really doing anything other than placing it close. Mine was one of the copies that cost about £25. It lasted 18 months of being folded and unfolded every day and thrown in the boots of cars and in the bottom of boats.
I also bought a Westcott Apollo 28" instead of the strobes kit, and it's a really fantastic softbox; very versatile because you can still get a soft spread for groups off it when placed several metres away, or if in really tight, you get some really lush drop-off. They're about £90 but worth it IMO. Phottix does a copy for about £50 and there are loads of copies on flea bay.
If I remember rightly, at last year's show they were selling modifiers similar to the ones in the Strobies set as individual items so you could buy what you needed. Plus, Viewfinder are dead cheap and the gear is half-decent.