|A stack of unopened 1990 Topps Traded wax packs.|
I just looked through both the Traded cards in my plastic storage boxes, and also at my 1990 Topps. It turns out that I had a bunch of 1990 Topps Traded mixed in with my 1990 Topps, because they're really quite similar. Now that they're separated out, I found a total of 43 cards of the 1990 Topps Traded set -- suggesting I opened 6 packs of 7 cards each, and maybe 1 pack had an extra card, or maybe I picked up a single card somewhere else over the years. I also have the complete factory set of 1990 Topps Traded.
Looking on eBay, I see that Topps tried Traded wax packs in 1985, then there were these in 1990, and they did it again in 1991. I can see why they tried, but in the end, I think the Traded sets aren't interesting enough to want to go through packs.