Best cartridge under $450? No Grados please

Seems like you have only a MM phono stage. If you have more gain that can handle a MC low output cartridge, but believe that you can't get a good one in your price category, take a look at a Denon DL103R, DL103S, or DL103D. They are all very good low output MC cartridges that are well under your price ceiling. For your "best cartridge under $450" classification, these have to be considered, although they do need about 65-70db gain in the phono stage.

Ortofon X5MC for about 125 street, or if you hunt you may find a new Kontrapunct B for about 500, or a Kontra A for less than 400.

I'd second the Denon DL-103D. I think it's one of the
great bargains in high end audio. It's available through
Denon USA for about $320. Search this forum or the Vinyl
Forum on audioasylum.com and you can find the phone number
for them. I'm using a Lehmann Black Cube SE phono preamp
which works nicely. Because the 103D only outputs about
.23-.25 mv it does require a higher gain phono preamp.

I saw on Ebay Dynavector 20X for $350 new. I think, the same man sells here too.But it was low output MC ;perhaps, he has high output as well,if you need one. What is your current set-up ?

There is no such thing as "best".