Audio Technica AT33EV different versions? On RP6?

I was thinking of trying a low output MC on my new rega RP6. The Audio Technica AT33EV looks like a potentially good one that will not break the bank.

Does anyone know if there are different versions out or NOS being sold between these multiple price points:

Amazon - $351
http://www.amazon.com/Audio-Technica-AT33EV-Moving-Cartridge/dp/B001J2KGDY

J&R - $500
http://www.jr.com/audiotechnica/pe/AT_AT33EV/#productTabDetails (some good reviews here)

Needle Doctor - $589
http://www.needledoctor.com/Audio-Technica-Cartridge-AT33EV?sc=2&category=363

Should I check for serial numbers, production dates or something else?

Has anyone tried this cartridge on rega arms, specifically the RP6 arm / table? Do people consider it a excellent, good or poor match? I've been told rega arms like high compliance carts and the AT33EV seems to be in the middle of that range. I would be using it with my Jasmine LP 2.0 mkII phono preamp. It looks like it comes with a nice protective stylus guart like the 95E or my current cart, the Ortofon MC-3 turbo.

Looking forward to see what people have to say about this combo. TIA.