Home Depot offers the Gladiator 48" GearLoft Shelf, model no. GAWA48SFRG, for $38.49. (Amazon charges the same but won't ship for a month or two.) Choose free in-store pickup to dodge the $9.49 shipping charge. That's $3 under our February mention and $13 less than the lowest price we could find, outside of the mention below. It measures 48" x 12" x 2.5" and has a weight capacity of up to 50 lbs.

A close price: Sears offers it for $38.87 with in-store pickup.