I picked up a SL1200 MK2 a few months ago for about $500. I have way more than $700 into it now, probably close to $2K. It came with the KAB RCA jack upgrade and had no dust cover. I bought a new dust cover for it and have since added the KAB fluid damper and put a Funk Achromat on it and replaced the feet with MNPCTECH feet. And then of course (at least with the RCA jack upgrade) you have cables and most importantly, the cartridge. And since I have a few cartridges, those need headshells, and then I need something to put the headshells in...
Up next, I just got some Fo.Q tape which I plan to use on the tonearm.
After doing all those things, it rivals the sound of my VPI Classic 2 with a Kiseki Blue NS cartridge and both sound better than my Marantz KI Pearl SACD player, which is no slouch and when new retailed for $3000.
And then there's my $2000 TEAC NT-505 streamer, which is probably my best sounding component, a very "analog" sounding digital device. However, it doesn't quite have the "magic" that's in the grooves of some of the better pressings I own.
In short, $700 for a turntable all in probably isn't going to rival a good CD player, although it might sound as good or better than a $700 CD player.
If you start with that $600 platform and are willing to chip away at upgrading it, then you can achieve great results. Of course you could just spend more and start with a better table and get similar results. It's been a lot of fun for me to tweak away on the Technics and take it to a point where it rivals a much more expensive table, but that's not for everyone.
Most of the budget belt drive turntables are not going to respond to upgrades as well as the SL1200 MK2, due mainly to it's solid build and isolation. If you don't start out with a good foundation, you're wasting money on upgrades.