Yes and no. If you buy just two or four fish, the gene pool is tiny. Within a couple of generations you will have a lot of slow-growing, low-fertility, or deformed fry. You get a lot of these with livebearers in the best of circumstances. So you really need a fair number of fish to build up a viable, safe population. This is the difference between quality breeders and "puppy farm" type breeders. Just look at the difference in quality of things like discus or Endler guppies. There's a huge difference between the fish produced carefully and the fish cranked out purely for profit.
Secondly, almost no-one makes money fish breeding unless they do it on a BIG scale. Teenagers living at home might make a profit, but that's because someone else is paying the bills for heat, light, etc. Once you have to cover these things yourself, as well as the hardware costs, food, medication, transport, shipping, etc then it becomes much less easy to make a profit. If it really was as simple as "buy two fancy guppies" then everyone would be doing it.
So, while breeding fish is a great hobby, go into it looking for fun, not money. If you happen to recoup some of your costs selling fish, then that's great. But don't bank on it.
Cheers, Neale
So what you mean is that I can buy the guppies and breed them without any signed permishion or anything like that? Well thats pretty darn cool!!! 8)