When considering buying a laptop, the first thing to do is to determine what your needs are: word processing, e-mail, browsing web pages, moving it around (size and battery life will matter), gaming (a very fast CPU, graphics chip and lots of RAM), on-line shopping, a database application (fast CPU, big hard drive), personal finance, photos (big hard drive), music (big Hard Drive).
Once you have figured out what you need decide how much you can afford to spend. Then check out IBM (Lenovo), Dell and Toshiba or HP. IBM and Toshiba make the best laptops and Dell spends the most on advertising, so has the best name, but perhaps the worst customer service reputation.
So, the question of new vs. used … depends upon your budget, battery needs and how much you will be using the unit. If you only have $300 to spend the only choice is refurbished. If you want a brand new battery then you will rarely find them in used laptops. As a matter of fact the battery might not even work. If you use the laptop a lot then seriously consider upping the budget and get new, as over 2-3 years the cost will be less.
So, once you have shopped around and narrowed it down to two choices then search google "used laptops" or "cheap laptop" and see who has the best deal. But remember the best price may not much matter if they have poor customers service, should you have a problem.