For under $500, you have two ways to go. The approved audiophile approach is an entry-level belt drive from Rega, Pro-Ject, or Music Hall. It hardly matters which one; they're very similar. They come with a good cartridge , but they're rather weak in the speed control department. Also, they lack a phono preamp, but you can get a decent one for about $50 from www.phonopreamps.com
The alternate route is the direct-drive Audio-Technica AT120, with an upgraded cartridge. www.lpgear.com
often has an upgrade package deal that's pretty good. Alternatively, you could call Needle Doctor and ask them what they'd charge to put a better cartridge on the thing. The 120 has a built-in preamp, so you're covered there. Because it's direct drive, speed control is much better, and you can buy as good a cartridge as you can afford.