MC cartridges

Do any of these companies keep these cartridges in-stock? I'd think they just order from the respective importer. I'd buy from who gives best discount, I've found some dealers that will offer upto a 20% off mrsp especially if bought from them in past. 

Not in the US, but seller kron here on Audiogon has a number of Dynavectors for sale.  Grey market, so no warranty.

Here ya go!
https://www.audioadvice.com/turntables/phono-cartridges

Do any of these companies keep these cartridges in-stock? I’d think they just order from the respective importer. I’d buy from who gives best discount...

Mehran and Robyn (links above) are two biggest distributors in the US, each of them have exclusives on some brands and other re-sellers buying from them (and may not have stuff in stock).

Asking for a discount is a bad manner, you must have a reason why you must get a discount. I think they are both mad about grey market dealers, so maybe it’s a good reason :)) Mehran at SoraSound will care about any cartridge purchased from him (warranty and even more), he can make a special offer if there is a reason for it.

Robyn offered trial on Miyajima cartridges in the past (maybe he can still do that), this is amazing MC cartridge, I own Kansui (it's mind blowing MC on the right tonearm). 

Asking for a discount is a bad manner, you must have a reason why you must get a discount.

There's no such thing as bad manners, especially if you're the buyer. Where'd you come up with that @chakster? Buying at full retail for high-end audio is only for select few products. You should always ask for best price and comparison shop.