I'd pay the $75 and get it done professionally. The Sailmaker will probably
do a better job than you can do and will probably put a conditioner back on
the sail.
You must have a pretty small boat to be able to wash your sail in a
commercial washer. How were you going to dry it?
Some of our friends with smaller boats have laid their sails out in their
drive ways and washed with garden hose and let the sun dry it. But sails
are a big investment. I'd take care of even a 15-year old sail if it is
still serving your purposes.
Gloria