No, not particularly rare or expensive, and I don't think it was an Anniversary model or even limited (I stand to be corrected if that is wrong). There are some for sale now or recently for around US$3,000. Trouble is, it was never quite right with all correct dial bits but in the standard 42mm asymmetrical case and with the standard bracelet. There were two references as I recall (3594.50 with bracelet and 3894.50 with a strap), so do your searches based on those. Here's a pretty good summary article of it and other "1957" models.
https://www.fratellowatches.com/speedy-tuesday-omega-speedmaster-57/