does it make sense to pay points to buy down the rate of a mortgage?

Usually not. Plug in the figures and see how long you would have to save that interest in order to pay back those discount points. Most of the time people either refinance or sell the home before they keep the loan even long enough to break even (much less come out ahead).

If you stay in the house for more than 6 years and 10 months, it is a great idea. If you sell or refinance before that time, you wasted your money.