If you specificially search for dust covers for turntable you will get attrocious prices. Few days back it occurred to me to search for printer cover with the same dimensions as my turntables and it was a success. You will find that these are available less than Rs 500 per cover. So if you are putting your turntable for long term storage this will do good.
e.g. this has fitted my technics turntable quite well
e.g. this has fitted my technics turntable quite well