A letter of intent to purchase the St. Louis Blues has been signed by Andy Appleby, who is the CEO of General Sports and Entertainment. No timetable has been announced as to when a final purchase may be made.A similar document was also signed by David Checketts earlier this year, but negotiations fell through.Appleby was a marketing executive for the Detroit Pistons and the Palace at Auburn Hills for 12 years before starting his sports and entertainment firm in 1998. In June, Bill and Nancy Laurie, of Columbia, put the team up for sale.