Alain,
I have dust covers that fit these two products. The yamaha is clear plastic and will only fit the 740. it sells for $15.00.
The other one is a black stretch type cover that fits inside a bag when you are not using it and stretches out of the bag to go around the keyboard. It sells for $24.00. I have also carried a cover made by Levy's that is a heavier material and is made to fit a particular keyboard. It sells for $32.00. I don't usually ship out of the US. Where do you live?
George Kaye