Many faucets are rebuildable, new washers even new stems.

Washers require a visable inspection, stems require a brand name.

Why do you want to replace them?

Measure the distance between the center of the hot and cold faucets.

Purchase a "widespread" faucet whose valves can be this distance apart. For example, the Delta Silverton and Delta Haywood faucet valves can be anywhere between 6" and 16" apart.

If the faucet includes a drain assembly, measure the size of the sink's drain hole to make sure it's the same size of that of the new faucet.

build.com, Home Depot, and Lowes are good sources for widespread faucets.