Lowe’s are very restricted in their sizes.Might disclose what sizes etc. Usually you can get boxes as low as 10 per if a standard size. Lowes, Home Depot etc. U-haul has big boxes, but they are expensive.
Uline has a pretty wide variety and minimum quantities are generally 5, sometimes 10 and, on occasion, single units (more expensive items). That being said, a quick search didn't turn up anything promising in the size you spec'ed. Still it perhaps is an option in the future. Also, have you tried the UPS Store?