The AT33EV has already been recommended, and you might try the AT33PTG/II (a linear contact stylus as opposed to the EV's nude elliptical). The PTG has a much smoother treble that the 150, but tracking is similarly excellent. The caveat is that the compliance of these carts is not quite optimal for medium mass arms like the Rega so you have to be careful about isolation from footfalls.
http://www.amazon.com/Audio-Technica-AT33PTG-Dual-Moving-Cartrige/dp/B00475S0BUIf you really want to spend in the $1-2K range, I'd try to hear a Benz for a very different, less neutral sound than the ATs, with more vibrancy in the midrange.