Sears offers two Gladiator 48" GearTrack Heavy-Duty Channels, model no. GAWC041PZY, for $13.89. (Add two to cart to see this price.) Opt for in-store pickup to avoid the $10.75 shipping charge. That's the lowest price we could find by $19. (For further comparison, we saw one channel for $7 in December.) It measures 48x6" and holds up to 75 lbs. per linear foot.
Of note, Shop Your Way Rewards members will earn a Sears credit with this purchase and may be eligible for additional credits and discounts.