Do people still have, let allown use yellow pages these days?
Have a look for bolts and nuts suppliers in a yellow pages or equiverlant. I use CBH fasteneres in Redditch (might not be local for you but just an example), not the cheapest but a fantastic range in stock at sensible prices and being a local supplier I can nip out and get any size bolt or nut I've required, waiting for internet delivery times is so passé

I do occasional buy fasteners off the net, though typically its boxes of 100 or more bolts at a time.