It costs about $25 per square foot to have brick repointed by hand. Work with an electric grinder runs about $5 per square foot as of 2015.
Repointing involves chiseling out and replacing the mortar that surrounds the bricks, while keeping them in place. Skilled workers can do this without damaging the hard fired shell of the brick and exposing its softer core.
Some homeowners attempt to save money by tuck-pointing, which means applying new mortar without chiseling out the old. This is just throwing money away, according to This Old House. It leaves a weak connection between the new and old layers of mortar. Sometimes it can even weaken the joint and make it easier for water to penetrate.