The night before Easter April 10, 1971 students packed Franklin & Marshall College"s Mayser Gymnasium for an evening of psychedelic music.For just $4.50, students saw the legendary Grateful Dead, with New Riders of the Purple Sage as openers.These days, $4.50 likely won"t even buy a beer at one of the upcoming Grateful Dead reunion shows.The band announced in January that four original Grateful Dead members Mickey Hart, Bill...