A great source for quality screws of all types is Mcfeelys.com. They also have detailed recommendations for proper fastener usage. I got tired of the cheap junk at most hardware and big box stores. I am not associated with McFeely's but if you like them, you can always send me money.

This thread reminds me of the fastener factory on Pulaski Avenue in Chicago that I use to pass back in the sixties that had a large billboard on top that stated "We sell screws, bolts, and NUTS TO YOU TOO!"