Federal TruBall Slugs have proven quite accurate in my Remington 870 Express (edged out only slightly in accuracy by Brenekke Black Magic Magnums) and most retailers in my area have them for $5-6 per box.
Smith, and Wesson, and Me. -H. Callahan
Well waddaya know, one buwwet weft! -E. Fudd
All bad precedents begin as justifiable measures. -J. Caesar