I think far far more CDX units were made than that... I own one I got from an extremely obscure pawn shop. It runs very well, and I found its output a little clearer than the output of the Gen Mark II. I has the same internal CD memory as a Sega CD unit, and it also (most importantly) has a headphone jack so you can get nice clear sounds! It takes 2 double A batteries to turn it into a Discman. It has a neat light-up LCD screen. Mine says it was made in February of 1994 in Japan.
I think it's "Story Time!"
I live in Canada, for starters. Anybody else from Canada will have heard of a store called the "Real" Canadian Superstore
Just so we're all on the same page, the Superstore is a sort of combination grocery/photo-electronics/cheap clothing store. Sorta like Wal-Mart but in reverse (i.e., they started with groceries, instead of with cheap other stuff.) Absolutely nothing remarkable about it. I can remember going into the Superstore near my house about 6 years ago and there was a big stack of boxes of CDX units for sale (for around $230 CANADIAN if you can believe that---I trust you can all figure out the exchange rate). Based on that observation, I'd like to think that a more substantial number was produced.
Just as an aside, that store also had a healthy stock of copies of Shining Force CD for sale. I bought one and liked the music but thought the game was rather... disappointing. Too bad I didn't buy more, I could be rich selling them on eBay...