Bruna replied to my email, and indicated that they do not provide a cover for the Graciella; Only, Simplex, Classic Signature , Pearl Contour Pearl and Sculpture keys have the plastic Dust Cover made by Begali. She also referred me to GIFTS4HAMS and G0PNM.
I got a reply from Pete at G0PNM, indicating the price for the Graciella is £35 plus shipping; no extra charge for engraving a call sign. Still trying to decide between these two options.