Look for Miller Specialty Tools, they are part of SPX corporation, which includes Kent Moore Tools and OTC Tools... you have found the manufacturer of most domestic and some foreign manufacturer's tools. They come up on EB pretty often, but the older and more useful the item is the more cash they want and the less often it appears.
As Doba pointed out this stuff is very expensive because most pieces are made only in sufficient quantities to support the dealer network who is forced to buy it. I many cases, the shop technicians find other tools they feel work better or the tool is not used for some other reason... the dealer winds up with an entire room full of this stuff, half used hard and half unused.
When the dealer closes, the tools are stolen or once in a while maybe one will purge old (very old) tools... that is how they show up for sale. Lots of closed Mopar dealers over the last couple of decades, some of the stuff went to the landfill... the rest someone wants to make a buck on.
THIS SELLER IS TRYING TO SCAM THE HOBBYISTS WITH A SET OF TOOLS THEY WILL LIKELY NEVER USE. The muscle car tie in is a great way to get the folks who no nothing, research nothing but have fat checkbooks and want to own everything... the poor guy might even think these would be display worthy with his collection.
The sad part is there might be a couple of real good tools in his sets that would be useful to somebody who works on their cars, but $600 seems pretty steep when I can't trace the tool numbers to their functions with my FSM. It's worth maybe $20 to me unless I see that "must have" tool in the mix... then maybe $50-$100. They're used specialty items that may never have a application for me, the popular stuff got aftermarket (Snap On, etc) versions that often work better and last better.
Tool collecting with use and function in mind can be a lot of research. The items are valueless without an application and need. I have over $1k worth of tools for removal of front accessory drive components including belts and fans for MB products... all factory tool items. I purchased them because it profited me to not search for the one worn out tool the dealer had for 20 techs. Most of that could be replaced in the aftermarket for $200-$300 today... and some of the more universal aftermarket designs work better and on more models, but it was the cost of doing business when I purchased.
I don't own a quality distributor wrench, I might purchase one someday, but I have found my preference for my 440's is to use a universal socket. On my GM's I have a good work around as well. For all of the cars I once thought I would like a specific wench for, their were other (sometimes better) tools in my collection to do the job. $600(ish) would buy a set of short combination wrenches and universal sockets in Snap On and be far more useful than this collection for almost anybody.