I found one at Ace's hardware for a time being not a perfect fit since local shop didn't have one in stock. For somehow you just can't buy the snap ring ( local shop said) had to buy both even it's a very old part number..But some how my little dog found it after few weeks.
My clutch lever was squeaking and I pulled the lever off to properly grease the pivot pin. I was telling myself, "you're going to lose the the snap ring you idiot". Thankfully it didn't go flying. I consider myself lucky.
Mine went flying when I was disassembling and lubing the clutch on my old Street Bob. I took the pin to lowes and found one that fit. I picked up 4-5 of them for a couple bucks.