Usually HF stands for Harbor Freight. Source for predominantly imported tools and supplies. Some of good quality, some of dubious quality. I buy from them. Usually located in good sized metropolitan area (Greenville, SC for me) and mail order. Just look over what you are interested in and determine if it is of the quality you want. For stamp sets, I've gone with the better stuff from a machinist supplier. Not the best, but the better. I stamp valve faces with the cylinder numbers, so I needed a little better quality.
NT usually stands for Northern Tool and Supply. Another supplier of imported tools and supplies. Used to be Northern Hydraulics back when they were predominantly a supplier of log splitter parts and other hydraulic oriented parts.
TSC is Tractor Supply Company. You see the pattern now.
HTH,
Mike Miller