I'm still using a ThinkPad R31 that I bought about 4 years or so ago. It's been excellent. Compared with the other brands that I've repaired for friends and colleagues, it's well ahead.
You can get a nearly-new later model (such as those mentioned above) for well within your price bracket. You get more for your money that way than buying new.
Some firms are refurbishing ThinkPads and sell them with "new" hard drives etc. I'd like one of those, but this one just keeps on working.