Firstly I'm really only referring to HW as being pretty worthless overall. Like I mentioned in the above post, yes there are a very few that might be worth anything.I would disagree with you on almost all your broad generalizations for 1:64 scale diecasts - even to the $0.99 HWs mainlines as way overly generalized.
I can still get them for $0.94 cents locally as the cheapest price point but at resale 90% of those casting can be had for as little as $0.50 a piece on the 2ndary market in a year or two (and sometimes even the same year.
As for the eye candy pieces they make - a > 100% return is the standard, 1000% is the mean/average and I have a few that would easily sell right now for 10,000% or more over their less than a dollar initial cost.
You should price range Maisto 1:64 castings right now....
Other 1/64s have retained or grown in value depending on the brand and some are worth scrap.