When I'm interested in learning about something new, that I'm interested in buying, I go on an eBay safari. Most recently, I was looking at cast iron skillets, but this is an exercise that could be carried out on almost anything. (cast iron, copper, knives, etc.)
Using the generic search words 'cast iron skillet,' I started learning about brands I never heard of. The Erie company later became Griswold, which was eventually absorbed by Wagner. A trip to Google taught me that there are whole online groups devoted to collecting Griswold cast iron, and they have online knowledge bases.
Forget your typical 3 bears (Small, Just-Right, and Large) sizes. I found skillets in numbered sizes ranging from 2 to 14. A number 3 skillet is 6 1/2" across. A number 14 is over 15 inches in diameter. ("Big enough to cook a full dozen eggs!") And in the 'also available from this seller' sections, I found skillet, griddles, dutch ovens, oval roasting pans, chef's skillets, deep skillets, skillets that doubled as lids, waffle irons, (actual iron waffle irons!), flop griddles*, and a whole lot more... and almost all in numbered sizes.
eBay can be like craigslist sometimes... people selling junk for anything they can get for it. But over the years, a class of professional eBay vendors has also arisen, and the variety of quality and restored vintage goods can be astounding. In the case of cast iron cookware, I found a number of vendors who strip, scrub and re-season the pans before selling them, with good reason: A good looking pan sells better, and it's less work for the buyer. But not only that, a lot of the older items just have more character than new stuff. I've found things on eBay that I didn't even know existed... and things that I can really appreciate the usefulness of. In other words, eBay is a way to shop not just for what's new, but to browse a selection of almost everything that has ever been made.
Some of the pans I found were well over 100 years old. They looked great. Compared with some of the 30 year old enameled cookware, they looked brand new. I wonder where these pans have been, and who they made breakfast for. I respect anything that was made well enough to last for 100 years, and still be in a good, functional condition.
*Flop griddle: This was a new one to me. This is a 2-part, articulated griddle for making pancakes. The pancake is poured in one side, and then 'flopped' over to the other side of the griddle to have the other side cooked.