Search the archives here for laundromats. There have been a ton of posts on the subject. There are posts from owners, sellers and buyers, and some great advice along with some web sites that cater to the business. One is www.coinlaundromat.net but I know nothing about it other than the URL.
I’m considering attending the “Coin Laundry: Basics for Beginners” seminar offered by the “Coin Laundry Association” on May 31 in Chicago. This seminar was also offered in Phoenix and Philadelphia earlier this year. They also have a seminar for experianced owners the day before. Info is at www.coinlaundry.org.