Buying to sell is a lot more economical, but then you have to have a lot of capital to start with which puts you in a risque situation before you even begin.
For example, a good friend of mine bought a run down house in a decent area at an auction for £60,000. Bargain initially, this was in 2007.
He renovated the house, which cost him I believe in the region of £30,000. He splashed out, made it look real authentic for the area, oozed class. Good kitchen, good size bathroom, and I believe there was a gas leak which needed fixed which cost a few bob, and obviously water leaks etc... Thus the property being cheap to begin with. He finished in December of 2007.
In April 2008 he finally found a buyer for his house. He sold it for £150,000.
If you add everything together. £60,000 for the house, say £35,000 in expenditures, inc estate agent fees etc. £95,000. Sold it for £150,000. £55,000 profit. Decent profit, and could go towards buying a new house.