This one is a very good price for OEM.
https://www.ebay.com/itm/324066055822?hash=item4b73d7968e:g:6VgAAOSwjAlaoXJ R
I have a couple of outdoor covers, but when I was looking for an indoor one I ended up buying this one. I`m very happy with it, it fits really nice and it keeps the dust out.
https://www.carcovers.com/covers/cars/porsche/boxster/2001/convertible/black-satin-shield.html#shopper_review_page