It Depends
If you don't mind "according to the book" sails (bear in mind that NOTHING is standard on a boat, the 23.5 included) any web site could get you a new sail. If there is something that doesn't match up will the mail order place make it right or is it a "special order and you have no rights". I humbly suggest going to a sail loft where you get a real person who probably knows what he's doing and will make the sail. That may cost a couple of bucks more but... A lot of places take your order and send it offshore to be made. Even some of the big name lofts do it. Know your loft like you know a good mechanic, they're better than the car dealer. Just my two cents.