Since it's a rear-seal faucet, it might be worth the couple of bucks to buy a generic rebuild kit. The 408 in the picture looks almost exactly like the generic chrome one off of ebay. I'm lucky in the my LHBS has an extensive set of gaskets, o-rings, and whatnot available, so if you're ever in the NW suburbs of Chicago, check out What's Brewing.
That being said, rear-seal faucets always stick and generally suck, so throwing any money at them is kinda a waste.
You could always email Perlick and ask as well.