A few years back, got my Mom an "upgraded" yellow gold chain at Sarraf for an inexpensive 14K pendant she bought. Their stuff is pretty commoditized and the pricing was fair. I think we bought one other chain from them.
If you are seeking a special "look," there seem to be a ton of sellers on IG making massive Cuban or curb link bracelets and chains (like up to a kg of presumably 14K).