I hate to break the news to you Abotelho but you are about 5-10 years too late. When I was in college from 2002-2007 I paid for most of my college and cost of living by building PC's for customers in the community. My little "business" got to the point where I actually thought when I graduated that I could grow it bigger and make even more money hiring some workers. I was wrong. By 2008 the cost of computers had come down considerably as well as the quality of computer parts had gone up dramatically. The days of needing a new computer every 2-3 years really ended around 2005 or so. Let me explain it this way to help give you a better idea. The sweet spot for a custom PC build where you will make profit was always $2,000-2,500.00 for everything (pc, monitor, keyboard,etc). Hardly anyone wanted to spend more than the 2500 but most realized you needed to spend around 2,000 to get a decent PC. BUT, by 2008 people realized that quality had caught up and competition was so stiff, that in order to keep my customers from going to circuit city, best buy, dell, or HP's websites to buy a PC, I had to lower my prices. By the end of 2009 it became a hobby and I was barely clearing 2-300 per build. AND nobody was really looking anymore. Why? Laptops were the craze by that point and PC's that I had built for customers in 2004,2005,2006 people were still using and were happy with. Also, Windows Vista bombing did not help me at all. Tons of people that I was hoping to get repeat business or referrals from had gone to Apple computers because of the negative press Vista had gotten. Now you have tablets to compete with and custom PC building in my opinion unless you are a big business like HP/Dell, is pretty much dead. So, I would say to you don't do this unless you want it to be a hobby. I build about 10 a year now for friends of friends of friends. I have built 3 this year. That's it. I made about $200 each.