Although I don't have direct experience to share, I don't want your post to be left dangling. Here's an
interesting thread where a PLC-590 owner upgraded from a Rega RB-251 tonearm to an SME 3009 to very satisfying results by his own account. He's obviously very handy with some serious metal-working tools, but maybe a tonearm upgrade would give you what you're looking for.
At first I was scratching my head at your request, but I think I understand. I myself have a Technics SL1210M5G with some modifications and I'm not ready to leave the propulsive pace and timing of direct drive for a low-torque-driven elastic belt.
Pioneer recently came out with the PLX-1000 direct drive turntable, which is similar to the SL1210 with twice the torque and better feet and damping (including an internally damped tonearm) for a mere $699. It might be worth a listen, but I doubt it has the sophistication and refinement of your Pioneer.
Beyond the PLX-1000, the price leaps into audiophile land. The least expensive DD I'm familiar with in this category is the
Brinkmann Audio Bardo, a bit more money than your budget, but the tonearm is extra.