While I haven't tried any out myself, some have mentioned GbodyParts.com, Dixiemontecarlodepot.com and Mikesmontes.com. All three sites are respectable, honorable, and small business sites. They are in it for the love of G-bodys and most have fulltime jobs elsewherere. I have purchased from two of them myself.
Do your research on the brands and continue to ask around. I have heard that some brands do not fit well. Browse around on Montecarloss.com as well, I know there were some recent posts on this.
Also, since you're getting the t-top kit, I would recommend just getting a full set for the doors. In the long run, you will spend less.
Good luck on your hunt and if you don't mind, keep me posted on what you find fits best. I might be looking in the near future as well.
