I need some turntable guidance

You can’t go wrong with new Technics SL1000R or SP10R
and if it’s too much then look for SL1200G
the GR is even cheaper 

I know where a supposed good deal is on a demo turntable for $10k. One of my questions is should I spend that kind of money or say are the differences marginal or great from a $5k to spending $10k? What do you get when you go up in price? Or what do you lose going down? Where is the sweet spot in higher end turntables?

it is really depends on a turntable, not just price tag, you can find a lot of mediocre turntable for insane price, you can also find cheap plastic belt drive turntables also for insane price for this technology.

My advice was to keep a brand new coreless Direct Drive from Technics, made in Japan. You can actually save a lot if you will stick to Technics new line of TTs. I’m pretty sure you can find a demo of Technics, so you can compare their top SP-10R to their cheaper but still nice SL1200GR. And if you want something in the middle there is an SL1200G (or GAE).

So many reviews online. With Technics you don’t have to spend a lot, but the quality will be superior to anything at the same price. And you can spend the rest on cartridge.

Technics is the answer to your question.

P.S. I don’t think you want to deal with vintage DD from the 70’s/80’s, but some of them are better than new Technics, you just need a knowledge to choose one. I am a big fan of vintage Direct Drive turntables and i have many. I don’t like belt drive technology at all.