Upgrade My Turntable - How Much Do I Need to Spend?

If I were you I would take a look at $2,000 turntables from Rega, Technics, Pro-Ject and VPI and pick the one you like.  Then get one of the PS Audio phono stages.  They list for $3,000 but go on sale for $2,000.  Or you might find one used.  Your Ortofon Blue can be upgraded to a Bronze by simply changing the stylus and you can hold off on that until you need a new one, but the Bronze is a very worthwhile upgrade and in your situation is your best option for the money.  Back to the turntables for a minute.  All four of the recommended brands are good, are competitive with each other, you can't go wrong.  Trust your heart and pick the one that appeals to you.  Don't let anybody talk you into going against your instinct.

Further thoughts, take a hard look at the new Denon turntable.  I think it lists for about $2,500 and looks like a winner too.

I've been playing in this sandbox since the early '70s. I bought an SP-10 new back in 1973. After restoration (by the late Bill Thalmann, RIP), it runs in my vintage system, replinthed with a Kuzma 9 " arm.

I have a bigger system that started in 2006 with a Kuzma Reference and Triplanar. I eventually upgraded to the XL ( a beoytch to isolate given its weight) and Airline. 

To me, the answer to the question involves the whole analog front end- turntable, arm, phono stage, cartridge, isolation (where necessary). You don't need to do multiple arms, though that gives you more flexibility, for mono, for low compliance cartridges, etc. 

I understand budgets but don't advocate brands. There are some good tables out there- I'd buy one that enables a separately purchasable arm. I can mess with the tube rectifier in the power supply to my phono stage and change the overall voicing of the system. 

So how to pick what's right for you?

Auditioning in dealerships is limited. Home trial is best, but not likely given cartridge damage. 

I've had several good tables over the years- all of it makes a difference. Vinyl is my main and largely definitive source. It takes work to get there. Part of it may depend on geographic location in terms of what is available to you. 

Elliot, You wrote, "Playing a Stereo Cartridge even if your Preamp has a Mono Mode: the cartridge will pick up any vertical movement: scuffs, surface dust, dirt in the grooves, very slight warps: then the preamp’s Mono Mode will DOUBLE the unwanted noise in both speakers." 
This is not the first time you have made that claim.  Can you provide some supporting reference?  What happens in a typical phonopreamp in mono mode is much like what happens in most modern mono cartridges, which are bridged internally to produce a mono signal.  So too are phonoline preamps when in mono mode; R and L channels are bridged.  This does not "double" noise produced by vertical motion of the stylus/cantilever, so far as I know.  I'm willing to learn if you provide a reference.  It also goes against all my direct experience using mono mode in the preamp; the treble is noticeably cleaner compared to playing a mono LP in stereo mode.  That in fact is the major benefit as I perceive it.

You have some good choices in mind.
i've owned the  Rega P6 and Riga turntables are really good. I have a clear audio DC performance and clear Audio makes tables in your price range that are excellent. As Others have said, I would encourage you to invest sufficient money on a separate phono stage to complement your system. In fact, I might concentrate on that first, because once that is covered, the phono stage will pretty much be with you forever as long as you like it. In my experience, the phono stage in your Mac set a pretty low ceiling on the rest of your system. Again, there are going to be lots of choices in any given price range that are good and you're going to get recommendations that match somebody else's personal preference. Personally, I think Sim Audio has a good line at various price points and Rega has some good products as well. Good luck.