For some Bay Area residents who really love their coffee, the best brew isn't found at a specialty shop but right in their own kitchen—after roasting the beans themselves.

For more than seven years, Lawrence Busansky, a 48-year-old finance executive in Orinda, has roasted coffee beans at home, squeezing in the time on Saturdays or at night after his children fall asleep. Working in his kitchen, he heats up a gadget that resembles a food processor to about 450 degrees and monitors...