When you say "overpriced," you may mean something more than price, such as quality of build or sound. That adds a layer of complexity that the gods of assessment would frown upon as "confounding." When I speak of being "overpriced," I'm speaking of a price that is simply marked way too high for the materials being sold - regardless of the genius in looks, sound or marketing.
On that note, I think every Grado above the SR-325 is "overpriced." Even if you factor in the price of mahogany, a $700 RS-1 is still ridiculously expensive for the materials employed. It gets even more so when you pay $1,000 for the GS-1000 (which uses a little more of that mahogany on the outside but whose space - inside the shell - can't be much, if any, bigger than the space inside the chamber of an RS-1). And if you think an additional $300 for a muffin top is egregious, what can you say about adding $700 to that for aluminum? Is aluminum that expensive? Is there really that much more aluminum inside a PS-1000 than inside a $300 325?
With Grado, you're not paying for materials. You're paying for the right to wear custom headphones from a boutique manufacturer. If you think the Grado family has a Stradivarius-like genius running through their gene pool, you'll pay for the privilege of wearing their top products. But when I look at the graphs or listen to all but the PS-1000 (which I have not heard), I'm skeptical of all this Grado fanboy mysticism.
Don't get me wrong. I think the folks paying $1,800 for a Sennheiser HD800 are also getting stung. They and the Gradoheads have every right to enjoy great sound. In a free market, a manufacturer can demand its price. If you don't like it, go somewhere else. There are lots of good headphones out there. There are even an assortment of great ones. But at some point, we aren't talking about build and labor. We're talking about fashion - though with a twist. We're talking about the joys and pleasures of trying on a top designer's best products. If you paid the same amount of money for a dress, or a great suit, you'd still be stung, but there'd be folks who don't get this who'd at least get that. I still scratch my head when I look at the price difference between cars with similar engines but different styling. Is the engine really worth $10,000 to $40,000 worth of difference in the actual price tag - particularly for a street vehicle whose maximum legal speed is going to be 70 mph? Yes, if you really want that hot, hot car. Will the ride be that different? I'm not so sure.
If you're paying more than a thousand dollars for a headphone, you're paying an awful lot of money for a pair of miniature speakers strapped to your ears. Unless there's a lot of cool bells and whistles, you're getting stung. In my opinion, the top-drawer Grados, Sennheisers, Ultrasone, etc. are overpriced. Don't even get me started on Bose. I speak as someone who loves his GS-1000 and RS-1, but who also loves his modded SR-60 (with open back, dolloped driver and modded cushions).