Pshaw. The only piece of equipment you really need to make decent wine is a 5-gallon bucket. A hydrometer and some plastic tubing comes in handy, but isn’t absolutely necessary. Decent wine kits at your LHBS will come out to around $2-4 per bottle.
I have a hard time accepting that they can produce good wine from just grape juice concentrate, water, and yeast in only a few days, no matter what technological tricks they use: warm, fast fermentation typically produces a lot of off flavors.
My guess is that the “grape juice and yeast” step is basically grape juice concentrate along with some sucrose or dextrose combined with a champagne or turbo yeast to produce the desired alcohol, and the final “sachet of ingredients” is basically a mixture of flavorings and “instant wine,” produced using a process similar to instant coffee, to make it taste good. The fact that it can’t be stored beyond 7-10 days because it’s “bottled under air, not an inert gas” raises my eyebrows. ALL wine is bottled under air.
The thing is, producing really good wine at home is downright easy. The equipment (basically, a couple of 6-gallon buckets, a corker, some plastic tubing, an airlock, and a few other odds and ends) will run you ~$100 at your LHBS, and a kit with enough grape juice, yeast, and preservative to make 30 bottles of wine will run $60-120. Aside from bottling, making a batch involves about 45 minutes of actual work spread out over a month or two.