Paintings. I'd love to have something unique, interesting and beautiful hanging on my rented walls. But the prices tend to be from 200eur upwards for A3 size ink work, decent paintings are probably more. I could justify a threefold price compared to a photo of same size, but not tenfold. I think the industry of painting art should change somehow. Devianart's order prints is going to the right direction, but they are still overpriced. PS. Started thinking painting as a service business and I think the most potential is at bathroom wall paintings. If you think about it, many people go approximately once per day to sit in bathroom for about 10 minutes. That's a long time to look at empty wall. And that's probably only time during the whole day they just look at an empty wall. And the scene of bathroom wall paintings is dominated by silly one liners in frames or something printed to toilet paper.
I don't know what it's like in your city, but in mine there's a lot of good stuff being done in university studios and there's a good art scene, though if you're not involved in it, it might be hard to find out about. I have a few friends that are painters and printmakers and they turned me on to something called "The Open Studios" which is an event that happens several times a year. Artists open their studios to the public to exhibit and sell their work. Often artists are willing to be flexible on pricing if they can see that the person asking for it is really into it or they might even be willing to trade pieces for services or goods. Anyway, you might check out your local universities for similar opportunities to get pieces of art at reasonable prices.
I study at one that includes industrial design. And I work at local "art center" and my grandmother is a painter. The thing is that if there is no price, I usually think it's not for sale. If there is a price, it's likely to be at least 200e. I would not like to ask "hey granma, can you give me this as a gift?". Because I've understood everyone who owns private company just hates to do free work for relatives. It doesn't pay anything and once you start, you notice you have 50 relatives who want something.