I have 296 kit previews tagged in LR. A few kits had multiple previews and there are probably a dozen or two (maybe) non-SSD kits, so probably 275. That includes all the kits I purchased by SSD designers, though, including designers who have left. I have no idea how many of those are by designers who are here now.
ETA: I have 718 previews for products that I can use at SSD. That includes kits, QA's, freebies, element packs, alphas, templates. Everything. And those are all by current SSD designers.