Your choices with the Thorens are pretty wide open. I'd likely avoid the higher compliance cartridges - a Shure V15 for example. Many cartridge prices have generally gone up as of January 1 of this year, so some popular choices that were in the $200 - 300 range are now in the $300 - 400 range.
You might still be able to find an Audio Technica AT-150MLX in your range, such as this example below:
http://www.jr.com/audio-technica/pe/AT_AT150MLX/
It would be on the lower end of the compliance range for your tonearm, but I think it would still make a good match.
Another option - and one of our good vendors sells this particular cartridge, would be the Ortofon 2M Blue. Look up Fred Longworth on AK and see if he's got any in stock.
RTOFON 2M BLUE SPECIFICATIONS
Output voltage at 1000 Hz, 5cm/sec. 5.5 mV
Channel balance at 1 kHz 1.5 dB
Channel separation at 1 kHz 25 dB
Channel separation at 15 kHz 15 dB
Frequency range 20-25,000 Hz
Frequency response 20-20,000 Hz + 2 /-1dB
Tracking ability at 315Hz at recommended tracking force 80 µm
Compliance, dynamic, lateral 20 µm/mN
Stylus type Nude Elliptical
Stylus tip radius r/R 8/18µm
Tracking force range 1.6 -2.0g (16-20 mN)
Tracking force, recommended 1.8 g (18 mN)
Tracking angle 20°
Internal impedance, DC resistance 1.3 kOhm
Internal inductance 700 mH
Recommended load resistance 47 kOhm
Recommended load capacitance 150-300 pF
Cartridge colour, body/stylus Black/Blue
Cartridge weight 7.2 g
Replacement stylus unit 2M Blue