Buy links

Is buying cheap one-way links a good idea?

There's an interesting thread on the value of buying cheap one way links over at DP. In short, some people say they are worthless because they are low quality links and some are not all that permanent. Then people like me (My DP username is "Jim") say that we don't expect much for 3 bucks a link, cheaper than any paid inclusion directory and at least we get some links that don't come from directory pages. They may not be valuable, but what do yo expect for 3 bucks a link?