Is there usually a dramatic difference between $5k and $10k cartridges ?

They will inevitably have different materials and design choices that ensure a different sound. Which one you like better may not be correlated to the higher price. If you’re talking about upgrading within one brand line then it’s a safer bet that the higher cost one might sound “better”, but even that’s not a 100% guarantee.

But most 5k and 10k carts will in fact sound pretty great overall; it will be hard to find a dud. At the very top tier prices the manufacturer can take extra special care selecting only the very best coils / motors - I think that’s what Koetsu did with the Blue Lace model, and it does sound better than other stone models to me.

mulveling, that’s what I assumed. No guarantee, let alone "dramatic difference".

@inna Well, it can actually be quite a significant difference, but most of it is usually "personality" rather than a difference of "quality" level. Moving coils each have a distinct sonic fingerprint caused by choices made on magnet, pole pieces, coils, wire, overall design - cantilever and stylus too!

A Van den Hul Colibri sounds worlds apart from a Koetsu. Both have their fans. There is only a small number of MC motor designs; many still use the classic magnet-yoke system which goes back to Ortofon’s SPU of the 1950s. Ortofon has used a very different motor design in high-end models since its Jubilee MC (coils mounted INSIDE the magnet in very compact form - look at MC100 or MC200 too). Clearaudios are using something different again (coils like a dumbbell with pivot in middle). Colibri is "monopole", no front yoke pole piece, which is why the motor sticks out so much (and probably contributes to its sibilance too). With the classic yoke designs, you get a classic warm "vintage" sound with "softer" magnets like alnico. Or you can "harden" it up and push it towards more modern hifi sound with neodymium. Samarium cobals sounds close to neodymium. Platinum magnets sound somewhat between the two extremes, but Koetsu bought them all up. Oh and Lyra uses a variant of the yoke, with non-magnetic pieces but an extra magnet mounted in front! I find this all fascinating.

If they sound "worlds apart" then is it possible that none of them sounds right ? Or it is more like fine musical instruments that are different but both sound right ?

Yes, that is correct - cartridges are not a great pursuit for those seeking an "ultimate truth" (whatever that is). I prefer to think of them as performance artists :) 

Anyone ever buy demo/used cartridges? Thoughts? Experiences?

I've bought plenty both new and used. Best is buying used from hobbyist audiophiles with stellar feedback who cleans their gear compusively (i.e. check the cart picks for a "dust beard", look for a clean stylus pic). Many of us also have large cartidge rotations, so no one cart gets too many hours. Never had any issues with cartridges bought selectively this way. Dealer demos can be OK-ish, but are usually not kept nearly as clean as the best hobbyists. And if you're buying from a gear flipper whose expertise caps out at fuzzy iPhone pics, good luck. 

But if the seller is at all honest, and their feedback is to be trusted, they should be able to accurately describe the cartridge's condition, age, and performance. I've actually had a much higher rate of various issues with used (active) electronic components.

$30k table, $15k arm, $25k phono stage

Agree with others - it’s a mistake to think like this. For example, the top-range Koetsu cartridges match brilliantly to Fidelity Research arms that can be found quite easily under $2K (used). There are other affordable arms they’ll sound great with too. You actually DON’T want to put them on a modern high-end straight, low mass, highly damped arm. That's not their sonic partner. It will sound dull and boring. 

$25k phono is gratuitous. Go for it, if you can and have the desire. But much more moderate stages can do wonderfully. The match of MC cartridge to MC stage is crucial (especially as lo-MC’s have lower output levels), but it’s not necessary to shovel anywhere near that much money in.

Same with the table. You can have well less than $10K total in arm, cartridge, phono - and still get the "full Koetsu" experience out of whatever stone you put on it.

Someone else said you can sometimes be pleasantly surprised by placing a very high-end component into a more modest system, and vice versa: placing a very budget component into a very high-end system. I’ve certainly found that can be true, in both cases.

Of course, I could not afford the setup that a 10K cartridge would require, but I have a question. What type of LP would be up to the task of producing such high quality sound? It seems to me that only the highest quality audiophile discs would justify such a cartridge. I don’t believe the run of the mill LP would benefit, but I may be wrong.

Literally any decent sounding LP - there are tons out there. And again, a lot of the difference is just "different sound" with "better" being harder to quantify and agree upon. You might be blown away by a $10K cartidge one day, only to later find a $2K cart you like even better. If you want to go for the most "accurate and resolving" cartridges, I'd probably look at the latest top-end Ortofons or (based on impressions of others - I have not heard these myself) the DS Audio optical carts. The couple times I heard an Ortofon Anna (which is now outdated) it sounded reminiscent of really good, very high-end digital. The A90, Windfeld MC and Ti walk that line a bit, too.

mulveling, judging by your description Ortofon doesn't sound appealing. Do you like Lyra cartridges ?

I actually did enjoy the Windfeld Ti and A90 - they're not completely dry & analytical, nor without their own unique charms. The Windfeld Ti is quite a punchy and dynamic cartridge, to go along with its high level of detail - it has some decent body to its mids - and its balance is not too tipped in favor of HF's. Also have to respect that Ortofon has really pushed the envelope of experimenting with technologies and designs. 

But in the end it was still sort of hit-or-miss; some days I loved it and others I'd just lose patience and return to the warm embrace of Japanese MC's. 

No Lyra's yet. I'm curious, but the rep of tipped-up HF has kept me away so far.