First "real" TT...

Hey all, I am looking at buying my first "real" TT, and I need some advice. I have a cheapo stanton str8-20 TT that I got at guitar center for $120 a couple years ago, just to play a few of my old man's records. I've recently found myself listening to it alot, and am starting to notice it's shortcomings. It has a Audio Technica "universal" $30 cart. So, as you can see, I have a pretty low-end setup. I'm looking for a new-to-me table and cartridge. Total budget: $500.
I've been looking at Pro-ject's Debut III, Rega Planar 1, various Thorens (used), technics 1200(used). I keep finding conflicting reviews of all these things, and honestly I don't know a damn thing about cartridges. Any help is appreciated.
Thanks, Nick