What Turntable to buy under $600 ?

None of the pick ups you listed are among the truly high performance cartridges I was alluding to. Those include Zyz Airy, Zyx UNIverse, Benz Micro Ruby, Shelter 90X, Dynavector XX and XV-1, vdH Colibri and Grasshopper, etc. I'm sure the 300 will track the cartridges you list but I maintain, quite accurately, that it will not extract all of the information that a better arm will.
The 250 and 300 are nothing more than entry level to mid-level performing arms. To speak of them in the same breath as world class tonearms such as Wheaton, Schroeder, Graham, etc. is not only disingenuous but bordering on heresy. Nobody but nobody with a high end reference level analog system uses the 250 or 300 simply because they are physically unable to handle elite cartridges. Sorry to hurt your feelings but facts are facts. Good luck.
S

Heresy is my bread and butter, no disingenuousness here, and "facts" as you say, are not facts, which IS disingenuousness. If the Regas can track upper-level Kisekis, then they can track upper-level Koetsus (as they in fact do). I fail to see how the list of cartridges you list differ physically so much from Kisekis and Koetsus, or indeed Denons and Audio Technicas and so cannot be tracked by a tonearm with excellent bearings and internal damping (i.e. the brilliant variable-thickness wall) and finally, proper mass-matching. Perhaps you can explain this "fact" to me. It's a new one on me that Koetsu, to name a current name, does not manufacture high-end cartridges, but evidently you read the high-end mags stuffed with over-priced new-and-improved goodies, judge by price tag and freshness (newer is better), and perhaps consider the Koetsus "passé". In recent tests/comparisons, the top-of-the-line Koetsu (Hi Fi + magazine) was not as good in some areas as the top-of-the-line Kiseki of the '80s period, there has been change yes, and improvement in some areas, but at a cost in other areas. It's easy to design for and listen for only Detail Uber-Alles, but unfortunately for you and too many misguided audiophiles, music is far more complex than that. I stand by my analysis of the extreme balance of the Rega tonearm (especially the RB300), a quality more elusive and hard to identify than the simple tinkling of bells. In other areas tonearms old and new surpass the Regas, but overall is another story. The reason most (not all) do not mount the list of "elite" cartridges you list on Rega RB250s and RB300s is simple-minded snobbery, Audio-as-Status, nothing else: these tonearms are too cheap, and hence cannot be any good, end of story. Evidently, the controversy over the quality of the Rega tonearms continues even if some are getting bored by their ubiquity: this controversy has everything to do with too high a level of performance for too low a price. And don't worry, you haven't hurt my feelings, you have heartened me to see that the Regas continue to generate some excitement, and confirm me in my opinion that price-tag and its attendant status - the reason for the controversy in the early days of its release - has far too great an impact on perception.

Back to the question at hand, here's a nice possibility-Microseiki

I had a P3 as my first 'phile table, and was pleased even before I knew it was fast. I did buy a used Sota Sapphire and was pleasantly suprised at all the new detail I could extract from a disc. The tonearm is a Rega 250, I got tired of the spring stories and turning the VTF dial to 3 as mentioned here on the 'Gon to eliminate the spring factor. (I just wanted to measure accuratley with a digital scale, by moving the counterweight with nothing else in the equation) The Sota is a good table in the used market, and are studier than the Rega if you happen to bump it. The Rega tonearms are a great buy with all the aftermarket endstubs and counterweights on Ebay and the like. Currently I use a ZYX Yatra on my Rega 250 and have tried a Shelter 901 too, both have made great music on this tonearm. A great tonearm if you don't want to break the bank. The 250 does not have the spring, but has plastic for the endstub and counterweight. I believe there is someone on Ebay that has both machined from copper for $60, not bad considering the Heavyweight and Kerry Audio F2 are both $100 and up.