I used to get stuff like that from the hardware shop in El Altet, they are super helpful and the prices are as good as you will find anywhere.
I just took a photo of what I needed, or took the part that needed replacing with me and they always had what I needed.
I replaced both mine, it’s an easy swap.
Just make sure you replace the bolts and washers that fasten the cistern to the pan to avoid leaks and definitely replace the O ring between the pan and cistern otherwise I guarantee you will have leaks every time you flush the toilet.
Regards all
John