Yes, I think those parts are overpriced as well, but nothing to worry about. The free market will work its magic and the one of three things will happen: they'll never sell at those prices, or the seller will lower the prices until they do sell, or a willing buyer will come along and pay those prices. I do not think any educated buyer should pay those prices, but it's not impossible that someone, somewhere might do it...certainly not me, however.
I don't think this will make any lasting difference to the restoration hobby in any meaningful way, to tell you the truth. I suspect the parts will languish on eBay for a long time. Anyone that is really into Simplex will do their homework, I imagine, and source their parts here, from fellow enthusiasts, or from Wayne before they'll pull the trigger on eBay parts with high prices.
But, at the end of the day all it takes is one guy that says "I gotta have that!" in order for the seller to realize those kind of prices.
I very carefully follow eBay for scooter & motorbike stuff (though I'm not buying Simplex stuff, so no competition for you guys) and I'm amazed at the prices some stuff I'd call scrap or junk actually sells for especially unusable frames, forks and wheels. There have been plenty of high list prices on nice items also that never sell, too. There is one particular Doodle Bug related piece I'd like to own (but don't "need") that the seller has priced far over market value (almost 3x). It has been relisted for 8 years for the exact same price with only a buy-it-now option. The seller won't entertain and offer of one cent less. Everyone that might have been interested in buying it saw it for sale years ago and decided the price was too high, but the seller keeps trying. That may be the fate of these Simplex parts.
On the bright side, at least they are for sale and not in a scrap yard headed for a crusher or on a container ship headed to an overseas steel mill.