Best cartridge under $450? No Grados please

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".

From my personal experience I would recommend the Goldring G1042 MM cartridge. It has a 6.5mV output & it really sounds excellent. Your present phono stage should work just fine with the G1042.
Here's their website:-
http://www.goldring.co.uk/

They also offer various MC cartridges such as the Eroica H (2.5mV output), which is also supposed to be a good buy.
FWIW. IMHO.