Yeah if DWC is the route you're going, you can easily build a better one yourself. Go to walmart and get an air pump, 1/4" tubing, and air stone, all from the aquarium section, and pick up a rubbermaid or bucket to use as your res if you don't already have a container in mind.. After that you just need net pots and a medium, such as the rockwool\hydroton. All of which are cheap, and you're done. That's all DWC is. An air stone inside of a tub full of water\nutes, with your plant dangling down above.
As was said though, that's a really small res, you'll have to refill it a LOT. Your plants would end up overcrowding each other and fighting for light in such a close proximity after just a few weeks. Size of the res\buckets you'll want depends on the space you'll be growing in, and space the cups out much more than they did. The the distance between the center of the cups would be relative to the size of the plants you'd like to grow. For a cloner, they could be right next to eachother. For a typical SOG, and 2-4 ft plants, I'd say at least 5-8 inches between the centers of 2" or 3" cups. 4 inch cups are especially large and not entirely necessary imo. In DWC, I think it's more dependent on the amount of space your roots have to go crazy, which eventually they'll grow out of your cups and in to the res, regardless of the size of the cups. The cups are simply there to support them above the res. 2-3" cups would be fine for plants up to 4-6+ feet, although I'd suggest planning for some sort of screens\stakes\supports for anything more than 3 feet or so to keep them from falling over. I'd also recommend the 'heavy duty' versions of cups, the price gap is minimal and they'll definitely hold up, while the cheaper versions are a bit more flimsy.
Or go the 3-5 gallon bucket route and do it hempy style, as was suggested (probably the easier transition if you're used to soil, has a similar feel to it, but with the added benefits of being hydro), or just throw an airstone in there for DWC. You can even get those net cup lids for buckets now. One plant for a 3-5 gallon res is much more practical than trying to stuff 4 in there and having to maintain it constantly. Seriously, it'd be at least once a day, if not twice even, during later stages. They drink up a lot. I've got a 15 gallon res that one 5-ish foot plant would empty in a day or two at the most. Also, remember that your res isn't going to be filled entirely. While I have a 15 gallon res, I only filled it with 10 gallons of water.
SH isn't too overpriced considering you get everything all in one package from one store, but that package specifically is definitely subpar IMO. It may not be bad for someone completely new to hydro, just because it'd be a good lesson well learned for only $35, but I'd personally prefer a system that I wasn't expecting issues out of from the beginning lol. They have better packages, but they have a higher markup too, meaning you'd save even more with a DIY version, and they're all seriously simple to do. Unless you just have more money than time, I'd suggest DIY. There's lots of simple guides and people that'd be willing to help with any issues, as well.
Also, yes, if you're talking about hydroponics in general vs soil? It's pretty widely claimed that hydro in general, provided the genetics\conditions\etc are the same, will cut down on overall growing time by as much as 2 weeks. I've personally yet to grow in soil or tried to compare though. So, that's only hearsay for me. You also hear claims of bigger and better yields blah blah, but I've seen some damn impressive soil and hydro grows, as well as some pretty pathetic soil and hydro grows. If we're talking like NASA quality grows here, then I'd expect hydro could potentially produce higher yields as well simply due to the extra control. To me, it seems like a 'KISS' thing, even though people say soil is the easy route. 'Oh, you don't need soil to grow? Well, screw it then!'.
