If you browse etsy.com, the lap size quilts range from $35 to $150. It will depend greatly on the technique used, hand-quilted vs machine vs tied. Pieced vs whole cloth vs rotary cut stripes etc.
Materials at JoAnn's prices are at least $25 (3-4 yards @ $3 + $10 batting + thread) and they can go up from there.
Hope that this helps.