What are my Herman Keiser Presidential golf clubs worth?

My husband was given the golf clubs belonging to his grandfather, who has now passed away. My husband has tried to get into golf and concluded it's not his thing so we'd like to sell them. Trouble is we don't know anything about golf clubs. I've tried googling what's written on the clubs and I'm not finding anything. Are they rare or something? They are made by Northwestern and they say Herman Keiser Presidential on them. Of the irons there are numbers 2-9 and one that says PW. Does that make a full set or should there be a number 1 as well? Of the woods there are numbers 1-4 that say Northwestern and a number 5 that says Spalding. Any guidance you can give on what we have or how to sell them for the best price (I don't even know a ballpark figure!) would be very appreciated. Many thanks.