I keep one pan for mooncup cleaning, because I don't really like the idea of mixing sanitary products with my food, and because we all share kitchen stuff in our flat. I'd feel guilty if I saw someone cooking in a pan I use for cleaning my mooncup, even if there's nothing technically unhygenic about it.
I've always boiled mine up for about 5 minutes to clean it, but I recently tried tablets for cleaning bottle-feeding equipment. The staining on the cup isn't all gone, but it's much better, and I didn't have to face the prospect of my flatmates coming in and wondering what the heck I'm cooking [I quote, from last year, 'What the devil are you doing?!...']. It was also good to just leave it for a few hours, rather than setting aside a particular time to clean it.
I got 64 tablets for £1.31 in Superdrug. Although my bills are currently covered in the cost of my accommodation, I reckon that sterilizing tablets would probably be cheaper normally, particularly if you split a pack with someone.