There's plenty of places!!!
www.thunderracing.com
www.tbyrnemotorsports.com
www.ls1speed.com (they deal with LT1's too)
www.fasttoys.net
www.bmrfabrication.com (suspension stuff, good & cheap)
www.lgmotorsports.com
www.mmsracing.com
www.moreperformanceinc.com
www.nu-tekmotorsports.com (great engines)
www.pcmforless.com (computer tuning, they do great chips for us 93's)
www.performancess.com
www.quicktimeperformance.com
www.slponline.com
These seem to be some of the more popular ones, and if you want good 93 specific tech information, might I suggest the
Speed Density LT1 Tech Forum . It's worth checking out, and there's a lot of knowledgable guys there. Happy part hunting!