I want to get some chain, but I can't seem to find decent selections. I usually buy supplies on eBay, but when it comes to chains I get lost in all this mumbo jumbo.
Maybe there are keywords I could be searching?
Or if there are reliable sites that make it easy?

Look in the jewelry aisle of Joann Fabrics. At least at my location, they have ALL KINDS of colors and thicknesses of chains.

I got a ton of chain and other jewelry supplies from Big Lots for a really great price! Their stuff changes though, so there's no telling what's in the ones in your area.

Try Goodwill, that's another great place to find it, just by recycling the chains you find there.

Fire Mountain Gems is reasonable, and there are lots of suppliers on ETSY.

Hobby craft! I work in a charity shop, so I generally ask to take the unsellable jewelery to take apart and recycle... You can ask at you local charity shop to give you any broken jewelery, they're usually more than happy to give it for free, cause it's going in the bin anyway.

Thanks for the ideas everyone! These are great!

Fire Mountain is great. If you're looking for something not in bulk, try Hobby Lobby's website.

Shipwreck beads is great in person - if you happen to be in the Lacey, WA area. Otherwise, Fire Mountain :)

Michaels is my favorite craft store but you can check out Joann like they said or even Walmart's craft section

Walmart has cute and cheap colorful chain. Also some regularly priced fancier chain. Some people use hardware stores for cheap chain. I found a lot on ebay of 19yds of chain for $4.66 free shipping. Message me if you want the url ^_^