If you don't find a used cover I believe you can find a semi-custom fitted classic Montauk cover at
http://www.carvercovers.com. We have one on our classic Sport 13 and it's a perfect fit as good as or better than custom covers we've used in the past and at a much better price. Ours is made of Sunbrella which I highly recommend. The cover is also towable and we frequently tow the 13 with the cover fifty miles to Gulf Shores and back with no problems. Several colors are available of which ours is Whaler Red which has held up very well.