Three free catalogs from Berea Hardwoods, Craft Supplies USA, and Penn State Industries should provide enough basic information on pen kits. There are other venders with catalogs like HUT a reseller of Berea kits, and Packard Woodworks, that sell PSI kits.
Craft Supplies, has no resellers for their products, so either order from catalog or website. Berea Hardwoods has several resellers some only sell through their website or store. Penn State has online resellers and stores that carry their kits.
Stores like Rockler & WoodCraft often change the name of pen kits supplied by Berea & PSI.
Few online pen kit suppliers by-pass Berea & PSI and buy direct from offshore manufacturer.
Easiest way to get answers on any pen kit, is check the instruction provided online.