Honestly, I would check the classifieds over on contour.org. Good deals pop up every now and then. As for new parts, not much of an aftermarket left for these cars. You can still find vendors selling brakes, pads, shocks/struts and springs in terms of suspension mods. Haven't seen seen sways, though. Have you checked with BAT?
On contour.org there is a group buy for a very nice rear stabilizer bar. For the front the OMP strut bar which you can purchase from BAT seems to be the most popular. You're going to get your best bang for your buck with just a bigger rear sway bar though.
Yea a bigger sway bar would work nicley, but if you put anything bigger on them you run the risk of breaking the mounting points. They're not made very well, I think this kinda funny since its an SVT.