Let's us suppose that the best business you have mentioned means business with least cost but best profits since your 20k-30k budget.Lucky for you, I happen to know a kind of business that meet your demands. One that I kenw from a improvisationa painting by a painter when i was studying in China.That is "varied decor mural", the first pioneer in no pen wall painting. It is a totally new home decoration brand which has set off a new decoration trend all over the world. One can decoration walls in his or her new house without pen. It takes less time than traditional wall paper and hand painting, 2 hours is enough. It is environmental, non-toxic, non-pollution, waterproof and without noise. Neither painting skill nor pen is needed. One’s profit can be maximized because there is no need to open a physical shop and only a 2000USD first purchase can make you a distributor . In a word, "varied decor mural" would be your best choice